IC-NRLF 


30b    t.3S 


i 


B 


John  Swett 


Elementary  Physiology  and  Hygiene 


THE    HUMAN    BODY 


ITS    HEALTH 

A  TEXT-BOOK  FOR  SCHOOLS,  HAVING  SPECIAL  REFERENCE  TO 

THE  EFFECTS  OF  STIMULANTS  AND  NARCOTICS 

ON  THE  HUMAN  SYSTEM 

BY 

WILLIAM   THAYER  SMITH,  M.  D. 


ASSOCIATE   PROFESSOR  OF   ANATOMY   AN£   PbtfSIOLOGY   lfc  DARTMOUTH 
MEDICAL  COLLEGE 


COPYRIGHT,  1884,  BY 
1VISON,  BLAKEMAN,  TAYLOR,  &  COMPANY 

PUBLISHERS 
NEW  YORK   AND  CHICAGO 


fiOUCATIQN  Dl 

EXTKACTS   FKOM    RECENT   LEGISLATION 

AFFECTING   THE    PUBLIC   SCHOOLS. 

r~j 


STATE   OF   MINNESOTA. 

SECTION  1.  That  all  school-officers  in  the  State  may  introduce  as  part 
of  the  daily  exercises  of  each  school  in  their  jurisdiction,  instruction  in 
the  elements  of  social  and  moral  science,  including  .  .  .  self-denial, 
health,  purity,  temperance,  cleanliness.  .  .  . 

STATE   OF    MICHIGAN. 

SECT.  15.  The  district  board  shall  specify  the  studies  to  be  pursued  in  the 
schools  of  the  district:  Provided  always.  That  provision  shall  be  made  for 
instructing  all  pupils  in  every  school  in  physiology  and  hygiene  with 
special  reference  to  the  effects  of  alcoholic  drinks,  stimulants,  and  nar- 
cotics generally,  upon  the  human  system. 

STATE    OF    NEW   HAMPSHIRE. 

.  .  .  And  in  physiology  and  hygiene,  with  special  reference  to  the  effects 
of  alcohpli<?  drinks,  stimulants,  and  narcotics  upon  the  human  system. 

'; ',/      ,  '</  ;&;z?k,T3  OF  NEW  YORK. 

Provision  shal\  be  rmade  by'th^  proper  local  school  authorities  for  in- 
str/Jctijii/j^l'^i^iJs 'fn;  all;  spools';  supported  by  public  money,  or  under 
State  control,  in'  physioTo'g.v'rtn'd  'hygiene,  with  special  reference  to  the 
effects  of  alcoholic  drinks,  stimulants,  and  narcotics  upon  the  human 

system. 

STATE   OF    OHIO. 

To  the  board  of  education  the  State  has  primarily  intrusted  the  respon- 
sibility of  seeing  that  her  teachers  are  grounded  in  all  the  dangers  that 
beset  her  youth,  and  that  they  are  disposed  to  arm  their  youth  with  the 
requisite  knowledge,  convictions,  and  resolution  to  guard  against  these 
dangers.  The  effect  of  alcohol  on  the  brain  and  nerves  —  its  innate  ten- 
dency, like  all  narcotic  poisons,  to  enslave  the  appetite,  and  lead  to  excess 
and  ruin  — should  be  clearly  made  known  to  every  youth  while  in  school. 
—  From  notes  explaining  school-law. 

STATE   OF   VERMONT. 

.  .  .  And  elementary  physiology  and  hygiene,  which  shall  give  special 
prominence  to  the  effects  of  stimulants  and  narcotics  upon  the  human 
system.  .  .  . 

%*  Several  other  States  have  passed  similar  laws. 


PREFACE. 


IN  making  this  little  book,  I  have  tried  to  give  to  the 
student  a  definite  impression,  in  outline,  of  the  structure 
and  functions  of  the  human  body.  To  this  end  I  have 
tried  to  omit  all  statements  that  would  confuse  the  picture 
by  overloading  it,  and  all  statements  that  could  not  be 
understood  by  those  who  will  be  its  most  numerous  read- 
ers. I  have  not  told  them,  for  example,  that  the  re-action 
of  the  saliva  is  alkaline,  and  that  of  the  gastric  juice  acid, 
because  for  many  of  them  that  statement  would  have  no 
meaning.  I  have  not  mentioned  the  names  of  many  of 
the  muscles,  because  it  is  difficult  and  unnecessary  to 
remember  them. 

The  laws  of  hygiene  are  given  in  connection  with  the 
facts  of  anatomy  and  physiology  from  which  they  are 
derived.  Learned  in  this  way,  they  will  remain  in  the 
mind  as  guiding  principles,  and  not  simply  as  the  dicta 
of  authority. 

In  treating  of  the  effects  of  stimulants  and  narcotics,  I 
have  endeavored  to  set  forth  facts  which  are  susceptible 
of  abundant  proof,  and  which  are  of  the  most  importance, 
practically,  to  those  for  whom  this  work  is  designed. 

WILLIAM  THAYER  SMITH. 
HANOVER,  N.H.,  August, 


CONTENTS. 


CHAPTER  I. 

PAGE 

DEFINITIONS  ...... 13 

Anatomy,  Physiology,  Hygiene. 


CHAPTER  II. 
THE  BONES  AND  JOINTS 17 

Section  I.  Uses  of  the  Bones.  Two  Cavities  in  the  Body.  Num- 
ber and  Distribution  of  Bones.  —  Section  II.  Bones  of  the  Head 
and  Trunk.  —  Section  IIL  Bones  of  the  Upper  Limb.  —  Section 
IV.  Bones  of  the  Lower  Limb.  —  Section  V.  Structure  of  Bone. 
—  Section  VI.  Chemical  Composition  of  Bone.  —  Section  VII. 
The  Joints.  Parts  which  compose  a  Joint.  —  Section  VIII. 
Growth  of  Bones.  Effects  of  Alcohol. 

CHAPTER  III. 
THE  MUSCLES 40 

Section  I.  Voluntary  and  Involuntary  Muscles.  Tendons.  Apo- 
neuroses.  Number  of  Muscles.  •*-  Section  II.  Properties  of 
Muscle.  —  Section  III.  Structure  of  Muscle.  —  Section  IV.  Mus- 
cular Exercise.  Reasons  for  its  Value.  Ends  to  be  sought 
by  it.  Cautions.  Muscles  of  Expression.  —  Section  V.  Effect 
of  Alcohol  and  Tobacco  on  the  Muscles. 


CONTENTS. 


CHAPTER  IV. 

PAGE 

WORK  AND  WASTE. —  THE  BLOOD 50 

Section  I.  Wear  and  Repair.  Sleep.  —  Section  II.  Materials  for 
Repair.  Air.  Food.  Water.  —  Section  III.  The  Blood.  Red 
Corpuscles.  White  Corpuscles.  The  Plasma.  Coagulation. 
Loss  of  Blood.  Causes  of  Impure  Blood. 


CHAPTER  V. 


THE  CIRCULATION 


Section  I.  Organs  of  Circulation.  Arteries.  Capillaries.  Veins. 
—  Section  II.  The  Heart.  The  Pericardium.  The  Auricles. 
The  Ventricles.  The  Tricuspid  Valve.  The  Pulmonary  Ar- 
tery. The  Pulmonary  Veins.  The  Semilunar  Valves.  The 
Mitral  Valve.  —  Section  III.  Action  of  the  Heart.  The  Heart 
a  Double  Pump.  The  Lesser  Circulation.  The  Greater  Cir- 
culation.—  Section  IV.  Sounds  of  the  Heart.  —  Section  V. 
Arteries.  Veins.  Capillaries.  Rapidity  of  Blood-Current. 
Points  in  which  Arteries  and  Veins  differ.  —Section  VI.  The 
Pulse.  What  the  Pulse  tells.  —  Section  VII.  Variations  in 
Blood-Supply.  —  Section  VIII.  Effect  of  Alcohol  on  the  Circu- 
lation. 

CHAPTER  VI. 

FOOD  AND  WATER,  STIMULANTS  AND  NARCOTICS 77 

Section  I.  Definition  of  Food.  Elements  in  the  Body.  The 
Work  of  Plants.  Flesh-eating  Animals.  Vegetable-eating 
Animals.  Milk.  Meats.  Starchy  Foods.  Graham  Flour. 
Sugar.  Fat.  Cooking.  Mineral  Substances.  Water.  Eat- 
ing arid  Drinking  Habits.  —  Section  IL  Tea  and  Coffee.  To- 
bacco. Opium.  Alcohol.  Chloral. 


CONTENTS. 


CHAPTER  VII. 

PAGK 

DIGESTION  AND  ABSORPTION.— THE  LYMPHATIC  SYSTEM 98 

Section  I.  The  Alimentary  Canal.  Mucous  Membrane.  Di- 
visions of  the  Alimentary  Canal.  Definition  of  "  Digestion/' 
Pancreatic  Juice.  Emulsions.  Chyle.  Lacteals.  Work  of 
the  Muscular  Walls  of  the  Canal.  The  Teeth.  The  Sali- 
vary Glands.  The  Stomach.  The  Gastric  Juice.  The  Liver. 
The  Pancreas.  The  Digestive  Apparatus.  —  Section  II.  Ab- 
sorption. Villi.  —  Section  III.  The  Lymphatic  System.  Tho- 
racic Duct.  Lymph.  Lacteals.  —  Section  IV.  Hinderances  to 
Digestion.  —  Section  V.  Effects  of  Alcohol  on  Digestion. 


CHAPTER  VIII. 

RESPIRATION  AND  THE  VOICE 121 

Section  I.  Air.  Respiration.  Composition  of  Air.  Nitrogen. 
Carbonic-acid  Gas.  Oxygen.  —  Section  II.  Structure  of  the 
Lungs .  —  Section  III.  The  Air- Passages.  The  Nose.  The 
Nerves  of  Smell.  Breathing  through  the  Nose.  Snoring. 
The  Throat.  The  Larynx.  The  Trachea.  The  Bronchi. 
The  Bronchial  Tubes.  —  Section  IV.  Breathing.  Process  De- 
scribed. —  Section  V.  Changes  in  the  Blood.  —  Section  VI.  Waste 
Matters  given  off  by  the  Lungs.  Changes  in  the  Air.  Venti- 
lation.— Section  VII.  The  Organs  of  Voice.  Cultivation  of  the 
Voice.— Section  VIII.  Effects  of  Alcohol  and  Tobacco. 

CHAPTER  IX. 

THE  NERVOUS  SYSTEM 143 

Section  I.  The  Brain.  Cerebrum.  Cerebellum.  Medulla.  Con- 
volutions. The  Spinal  Cord.  Membranes  of  the  Brain  and 
Cord.  Gray  Matter.  White  Matter.  Nerve-Cells.  Nerve 
Fibers.  —  Section  II.  Action  of  the  Nervous  System.  Reflex 


CONTENTS. 


CHAPTER  IX.— Concluded. 

PA  SB 

Action.  Winking.  Coughing.  Sneezing.  Sensory  Fibers. 
Motor  Fibers.  —  Section  III.  Seat  of  the  Higher  Faculties.  — 
Section  IV.  Nervousness.  Habit.  Exercise  for  the  Brain. — 
Section  V.  Effects  of  Alcohol  on  the  Brain  and  Nervous 
System. 

CHAPTER  X. 
THE  SKIN.— THE  EAR.  — THE  EYE 156 

Section  I.  Structure  of  the  Skin.  Epidermis.  Derma.  Pa- 
pillse.  Sweat-Glands.  Perspiration.  The  Hair.  Sebaceous 
Glands.  The  Nails.  Uses  of  the  Skin.  Bodily  Heat.  How 
Heat  is  equalized  in  the  Body.  Clothing.  How  the  Body  is 
cooled.  —  Section  11.  Care  of  the  Skin.  Colds.  Rubbing  the 
Skin.  Bathing.  Cautions  in  Bathing.  —  Section  III.  The  Ear. 
Description  of  its  Parts.  How  we  hear.  Ear-ache.  —  Sec- 
tion IV.  The  Eye.  Description  of  Parts.  How  we  see. 
Causes  of  Trouble  in  the  Eye.  Too  Long  Sight.  Too  Short 
Sight.  Causes  of  too  Short  Sight.  Care  of  the  Eyes.  Color- 
Blindness.  —  Section  V.  Effects  of  Alcohol  and  Narcotics. 

APPENDIX. 

WHAT  TO  DO  IN  CASE  OF  ACCIDENT .    181 

Fainting.  Fits.  Sunstroke.  Shock.  Fractures  and  Disloca- 
tions. Bleeding.  Poisoning.  Drowning. 

GLOSSARY 189 

INDEX  197 


LIST  OF  ILLUSTRATIONS. 


COLORED  ILLUSTRATIONS. 

PAGE 

GENERAL,  REPRESENTATION  OF  THE  MUSCULAR  SYSTEM   .        .  38 

THE  HEART  AND  LARGE  BLOOD-VESSELS 58 

No. 

1.  THE  SKELETON 15 

2.  THE  SKULL 19 

3.  SECTION  OF  THE  BACKBONE      .        .       .        .        .       .       .20 

4.  A  VERTEBRA 20 

5.  THE  THORAX 21 

6.  THE  STERNUM 22 

7.  BONES  OF  THE  UPPER  LIMB 23 

8.  THE  SCAPULA 23 

9.  THE  HUMERUS .  24 

10.  BONES  OF  THE  FORE-ARM 24 

11.  BONES  OF  THE  HAND 25 

12.  BONES  OF  THE  LOWER  LIMB 26 

13.  THE  FEMUR 26 

14.  THE  PATELLA 26 

15.  BONES  OF  THE  LEO 27 

16.  BONES  OF  THE  FOOT 27 

17.  SECTION  OF  THE  FEMUR 28 

18.  THE  PERIOSTEUM 29 

19.  A  BONE  AFTER  SOAKING  IN  HYDROCHLORIC  ACID        .        .  30 

20.  JOINTS  OF  THE  SKULL  31 


10  LIST  OF  ILLUSTRATIONS. 

No.  PAGE 

21.  THE  IJ IP-JOINT 32 

22.  THE  SHOULDER-JOINT 33 

23.  BACK  OF  THE  LOWER  LIMIJ .41 

24.  BICEPS  MUSCLE 42 

25.  FIIJEIIS  OF  VOLUNTARY  MUSCLE 43 

20.  FIBERS  OF  INVOLUNTARY  MUSCLE 43 

27.  RED  CORPUSCLES  OF  HUMAN  BLOOD 53 

28.  RED  CORPUSCLES  OF  FROG'S  BLOOD 53 

29.  REPRESENTATION  OF  A  SECTION  OF  THE  HEART  ...  62 

30.  SEMILUNAR  VALVES  OPEN 63 

31.  SEMILUNAR  VALVES  PARTLY  CLOSED 64 

32.  REPRESENTATION   OF  THE   GREATFR  AND  LESSER  CIRCU- 

LATIONS        66 

33.  REPRESENTATION  OF  THE  ARTERIAL  SYSTEM     ...  68 

34.  CAPILLARY  PLEXUS    ...               70 

35.  VEIN  LAID  OPEN,  SHOWING  THE  VALVES   ....  70 

36.  A  DROP  OF  MILK  MAGNIFIED,  SHOWING  THE  OIL-GLOBULES  .  82 

37.  ALIMENTARY  CANAL  FROM  THE  (ESOPHAGUS  DOWN.       .  99 

38.  INCISOR  TOOTH  SAWED  IN  TWO 104 

39.  MJLAR  TOOTH  SAWED  IN  TWO 104 

40.  THE  SALIVARY  GLANDS 105 

41.  STOMACH  GLANDS  OF  A  PIG 107 

42.  THE  LIVER,  AND  OTHER  ORGANS  OF  DIGESTION    .                .  108 

43.  VILLI  OF  THE  SMALL  INTESTINE Ill 

44.  VILLI  SHOWING  VESSEI  s    .        .        .        .        .        .        .        .111 

45.  LYMPHATICS  OF  ARM -PIT 113 

46.  LYMPHATICS  OF  INTESTINE 114 

47.  LUNGS  IN  POSITION 124 

48.  GILLS  OF  AN  EEI 125 

49.  SECTION  OF  LUNGS  .                       126 

50.  SECTION  OF  NASAL  FOSSAE 128 

51.  THE  CHEST,  SHOWING  DIAPHRAGM       .        .        .        ,        .  131 

52.  THE  LARYNX 138 

53.  REPRESENTATION  OF  THE  NERVOUS  SYSTEM      ...  142 


LIST  OF  ILLUSTRATIONS.  11 

No.  PAGE 

54.  BRAIN  AND  UPPER  END  OF  SPINAL  CORD,  WITH  NERVES 

COMING  FROM  THEM 144 

55.  BRAIN  AND  SPINAL  CORD,  WITH  NERVES  COMING  FROM  THEM,  145 

56.  NERVE-CELLS 146 

57.  NERVES  OF  THE  ARM 147 

58.  NERVES  OF  THE  FORE-ARM  AND  HAND 148 

59.  SECTION  OF  SKIN 157 

60.  PAPILLAE 158 

61.  PAPILLARY  RIDGES  IN  THE  SKIN  OF  THE  PALM,  SHOWING 

THE  PORES 158 

62.  SWEAT-GLAND,  WITH  CAPILLARIES  SURROUNDING  IT        .  159 

63.  SECTION  OF  SKIN  SHOWING  ROOTS  OF  HAIR  .        .        .        .160 

64.  THE  EAR 167 

65.  BONES  OF  THE  EAR 168 

66.  THE  EYE 170 

67.  SECTION  OF  THE  FRONT  OF  THE  EYE 171 

68.  LACHRYMAL  APPARATUS 172 

69.  MUSCLES  OF  THE  EYE-BALL  172 


THE  HUMAN  BODY, 


CHAPTER  I. 
DEFINITIONS. 

SECTION  I. — 1.  If  we  wish  to  study  a  machine,  such 
as  a  clock  or  a  steam-engine,  we  take  it  to  pieces,  and  ex- 
amine each  part  separately.  We  inquire  what  each  part 
is  called,  what  it  is  made  of,  and  how  it  fits  in  with  the 
other  parts.  We  then  ask  what  is  the  use  of  each  part, 
and  how  it  works.  Knowing  these  things,  we  understand 
the  machine  and  its  action. 

2,  The  human  body,  which  is  the  most  wonderful  of 
all  machines,  is  to  be  studied  in  this  way. 

Anatomy  names  and  describes  its  parts.  It  tells  us 
their  size,  weight,  shape,  color,  texture,  and  composition ; 
their  position,  and  relation  to  other  parts. 

Physiology  acquaints  us  with  the  action  of  each  part, 
and  the  work  that  it  does.  It  tells  us  how  it  acts,  when 
it  acts,  what  makes  it  act,  and  what  is  the  effect  of  its 
action. 

Anatomy  may  be  studied  in  the  lifeless  body. 

Physiology  must  be  studied  in  the  living  body. 

Anatomy  is  well  known,  because  all  the  parts  of  the 
body  have  been  carefully  studied  and  described. 

13 


14  f  t^ttifi  HUMAN  BODY. 


^Physiology  is  oiily  .partially  known.  There  are  some 
parts  of  the  body  whose  use  we  do  not  know.  In  those 
parts  with  which  we  are  better  acquainted  we  find  much 
that  we  do  not  understand.  But  many  learned  men  are 
devoting  their  whole  time  to  this  study,  and  are  con- 
stantly adding  to  our  knowledge. 

By  combining  the  teachings  of  Physiology  with  what 
we  know  by  experience  we  construct  the  science  of 
Hygiene.  From  its  principles  we  derive  rules  for  the 
preservation  of  health. 

Anatomy  is  a  science  of  Structure. 
Physiology  is  a  science  of  Function. 
Hygiene  is  the  science  of  Health. 


QUESTIONS. 

SECTION  I. — What  is  the  natural  method  of  studying  the  body? 
What  does  Anatomy  tell  us  of  the  body  ?  What  does  Physiology 
tell  us  of  the  body  ?  Can  Anatomy  be  studied  in  the  living  body  ? 
Can  Physiology  be  studied  in  the  lifeless  body?  Which  is  most 
thoroughly  known, — Anatomy  or  Physiology?  Define  Anatomy. 
Physiology.  Hygiene. 


Inferior  Maxillaty. — 

Cervical  Vertebrae. 

Scapula. 

Humerus.' - 

Lumbar  Vertebrae. 


Car])us. 
Metacarpus. 


Tibia. 
Fibula 


Temporal. 


Clavicle. 


Innominate. 


-Pelvis. 


Patella. 


Tarsus. 
Metatarsus. 


,.-  Phalanges. 


Fig.   1. 


16 


HUMAN   BODY. 


THE     SKELETON. 


The  Head,  28  Bones. 


Occipital  (base  of  skull} 1 

Parietal  (sides  of  skull) 2 

Temporal  (temples) 2 

Frontal  (forehead) 1 

Sphenoid  (behind  the  face) I 

Ethmoid  (behind  the  face) I 

Nasal  (bridge  of  nose) 2 

Tomer  (between  nasal  fossa)    ....  1 

Turbinated  (on  walls  of  nasal  fossae)   .  2 


Palate  (back  part  of  roof  of  mouth) 
Lachrymal  (in  orbit)    ..... 

Malar  (cheek-bones) 

Superior  Maxillary  (upper  jaw)  . 
Inferior  Maxillary  (lower  jaw)  . 
Malleus  (in  the  ear) 
Incus  (in  the  ear) 
Stapes  (in  the  ear) 


.  2 

.  2 

.  2 

.  2 

.  1 

.  2 

.  2 


Vertebrae 

Sacrum      i-   (backbone) 

Coccyx 


The  Trunk,  52   Bones. 

Hyoid  (in  the  neck) 1 

Bibs 24 

1    Sternum  (breast-bone) 1 


The   Upper  Limbs,  64  Bones. 


Scapula  (shouldtr-blade) 2 

Clavicle  (collar-bone) 2 


Ulna  (fore-arm) 2 

Carpus  (wrist) 10 


Hnmerus  (arm-bone) 2    Metacarpus  (hand) 10 

Radius  (fore-arm) 2    Phalanges  (fingers) 28 


The  Lower  Limbs,  62   Bones. 


Innominate  (hip-bone) 2 

Femur  (thigh-bone) 2 

Patella  (knee-pan) 2 

ttbia  (leg) 2 


Fibula  (leg) 2 

Tarsus  (ankle,  heel,  instep)  «...     .14 

Metatarsus  (flat  of  foot) 10 

Phalanges  (toes) 28 


THE  BONES  AND  JOINTS.  17 


CHAPTER  II. 
THE    BONES    AND    JOINTS. 

SECTION  I.  —  1.  The  bones  are  the  framework  of  the 
body.  When  joined,  as  in  the  living  man,  they  constitute 
the  skeleton.  They  serve  three  purposes:  — 

1.  They  give  the  body  shape  and  firmness  of  outline. 
The  soft  parts  which  cover  them  add  grace. 

&.  They  act  as  levers  by  which  the  muscles  attached 
to  them  move  the  body. 

s.  They  protect  important  organs. 

2,  There  are  two  main  cavities   in  the  body  formed 
wholly  or  in  part  by  the  skeleton;  viz., — 

1.  The  cavity  of  the  skull  and  spinal  column.      The 
skull  contains  the  brain,  and  is  a  tight  box  whose  wralls 
are  strong,  and  which  is  so  shaped  as  to  resist  great  press- 
ure.    There  are  no  openings  into  it  except  those  small 
ones  through  which  blood-vessels  and  nerves  pass  in  and 

SUGGESTIONS  TO  TEACHERS.  —  1.  Every  school  in  which  anatomy  and 
physiology  are  taught  ought,  if  possible,  to  have  a  human  skeleton.  Lack- 
ing this,  the  next  best  thing  is  to  have  the  skeleton  of  some  quadruped. 
The  general  resemblance  will  be  sufficient  to  make  it  a  good  illustration  of 
the  text.  If  you  have  no  complete  skeleton,  get  dried  bones,  —  beef-bones, 
mutton-bones,  vertebrae,  long  bones,  jaw-bones.  Have  them  sawed  in  dif- 
ferent directions.  Much  can  be  learned  from  them.  The  differences  be- 
tween dried  bone  and  fresh,  living  bone  must,  however,  be  borne  in  mind. 
The  experiments  of  softening  a  bone  by  maceration  in  weak  hydrochloric 
acid  for  a  few  weeks,  and  of  removing  the  animal  matter  by  burning,  are 
easily  tried. 

2.  The  different  parts  of  a  joint  can  be  shown  in  a  sheep's  leg. 


18  THE   HUMAN  JiODY. 

out.  The  great  opening  at  the  base  of  the  skull  connects 
its  cavity  with  the  spinal  canal,  and  is  fully  an  inch  in 
diameter.  The  other  openings  are  very  much  smaller 
than  this. 

The  spinal  canal  is  also  well  guarded  by  its  walls,  and 
by  bony  projections.  It  contains  the  spinal  cord. 

2.  The  cavity  of  the  trunk.  This  is  divided  by  a 
horizontal  partition,  called  the  diaphragm,  into  two  parts. 
The  upper  part  is  the  thorax,  or  chest;  and  the  lower,  the 
abdomen  and  pelvis. 

The  thorax  is  a  bony  cage  formed  by  the  backbone 
behind,  the  ribs  at  the  side,  and  the  breast-bone  in  front. 
It  contains  the  heart  and  lungs.  These  organs  need  to 
be  guarded  against  blows  or  pressure,  but  they  are  not  so 
easily  injured  in  this  way  as  the  brain  and  spinal  cord. 
The  thorax  is,  therefore,  not  so  close  a  box  as  the  skull. 
Moreover,  it  is  needful  that  the  walls  of  the  thorax  should 
be  movable  in  order  that  we  may  breathe.  The  thorax 
is  so  made  that  it  gives  sufficient  protection  to  the  organs 
wThich  it  contains,  and  at  the  same  time  it  can  enlarge 
and  contract. 

The  abdomen  is  not  as  well  guarded  as  the  thorax. 
There  is  no  bony  wall  in  front;  and  the  intestines  are 
easily  wounded,  though  they  bear  pressure  and  displace- 
ment much  better  than  the  heart  and  lungs.  But  if  the 
abdomen  were  walled  in  front,  like  the  thorax,  we  could 
not  bend  our  bodies.  For  purposes  of  motion,  and  to 
permit  the  expansion  of  the  intestines  after  a  full  meal, 
they  are  left  partially  unprotected. 

The  pelvis  (Latin,  pelvis,  a  basin)  is  formed  by  the  hip- 
bones and  the  sacrum  and  coccyx.  Its  contents  are  well 
guarded  by  those  thick  bones. 


THE  BONES  AND  JOINTS. 


19 


3,    There  are  206  bones  ia the  body:  — 
In  the  head 


f  spinal  column  ....     26 

In  the  trunk     .  ]  ribs 24 

sternum 1 

I  hyoid 1 

In  the  upper  limbs 64 

In  the  lower  limbs 62 

206 

BONES  OP  THE  HEAD  AND  TRUNK. 

SECTION  II.  —  1,  The  skull  is  poised  on  the  top  of  the 
spinal  column,  and  contains  twenty-eight  bones.  In  the 
young  infant  they  are 
loosely  united,  but  in 
time  many  of  them 
become  welded  to- 
gether so  that  they 
can  not  be  separated. 
The  lower  jaw,  and 
the  small  bones  of  the 
ear,  are  the  only  ones 
of  them  that  are  mov- 
able. Besides  contain- 
ing the  brain,  the  skull 
protects  the  organs  of  Fig.  2. 

hearing,    Of    Smell      Of  THE  SKULL.  — 1.  Frontal  bone.    2.  Parietal  bone. 

_,       f  3.  Occipital   bone.      4.  Temporal    bone.      5.  Nasal 

VlSlOn,  and  OI    taste.  bone.    6.  Malar  bone.     7.  Superior  maxillary  bone. 

2,     The      SDinol      C0l~  ***  Lachrymal  bone.    9.  Inferior  maxillary  bone. 


umn,  or  backbone,  consists  of  twenty-four  vertebrae,  the 
sacrum,  and  the  coccyx.  The  vertebrae  (Latin,  verier e,  to 
turn)  are  so  called  because  they  form  an  axis  on  which  the 
body  turns.  They  are  irregular  in  shape,  and  consist  of 


20 


THE  HUMAN  BODY. 


a  body  and  an  arch.  They  have  projections  called  pro- 
cesses, to  which  muscles  are  attached.  When  they  are 
joined  in  position,  the  arches  to- 
gether constitute  the  spinal  canal, 
and  the  bodies  form  a  solid  col- 
umn for  support.  Between  the 
bodies  are  cushions  of  a  tough  and 
elastic  substance  called  fibre-car- 
tilage. Each  is  about  one-fourth 
of  an  inch  thick,  and  is  firmly 
united  to  the  bone  above  and 
below.  They  serve  as  springs  in 
the  column,  and  allow  a  twisting 
motion. 


Fig.   4. 

A  VERTEBRA.  —  1.  Body.    2.  Pro- 
3.  Spinal  canal. 


E-   o 


The  sacrum  is  a  wedge-shaped 
bone,  which  fits  in  between  the 
hip-bones. 

The  coccyx  is  the  end  of  the  column,  and  is  a  small, 
curved  bone,  commonly  in  two  or  more  pieces,  which  are 
united  by  joints. 


THE  BONES  AND  JOINTS. 


21 


3,  The  spine  in  a  baby  is  perfectly  straight,  and  his 
back  flat.  As  he  grows  and  walks  the  spine  becomes 
slightly  curved  backward  in  the  region  of  the  shoulder- 
blades,  and  forward  at  the  waist.  This  is  natural.  But 
frequently  the  curve  of  the  back  becomes  too  great.  The 
shoulders  are  drawn  forward,  and  the  chest  flattened. 
This  makes  a  stoop.  It  is  caused  by  weakness  of  the 
muscles  which  sustain  the  back  and  head,  or  indolence 
and  carelessness.  It  makes  an  ungraceful  shape,  and  is 
injurious  because  it  compresses  the  heart  and  lungs,  and 
checks  their  free  action.  An  erect  posture  and  a  full 
chest  should  be  cultivated.  To  this  end,  the  muscles  of 
the  chest  and  trunk  must  be  kept  vigorous  by  exercise. 


1st  rib. 


Clavicle. 


False  ribs. 


Fig.  5.     THE  THORAX. 

The  natural  curves  of  the  spine  are  forward  and  back- 
ward. A  curve  to  one  side  is  unnatural  and  a  deformity. 
It  comes  from  bodily  weakness,  lack  of  air  and  exercise, 


22  THE  HUMAN  BODY. 

and  from  standing  on  one  foot  habitually,  or  sitting  much 
of  the  time  at  a  desk  or  table  with  one  arm  resting  upon 
it  while  the  other  hangs  down. 

4,  The  ribs  and  breast-bone  with  the  backbone  form  the 
thorax.  The  ribs  are  twenty-four  in  number,  twelve  on 
each  side.  They  are  joined  to  the  backbone  behind.  The 
first  seven  are  called  true  ribs.  They  are  connected  with 
the  breast-bone  by  the  costal  cartilages.  The  last  five  are 
called  false  ribs.  They  are  not  directly  connected  with  the 
breast-bone.  The  last  two  false  ribs  are  called  floating-ribs, 
because  their  front  ends  are  not  joined  to  any  bone. 

The  costal  cartilages  are  continuations  of  the  ribs. 
Cartilage  is  more  elastic  than  bone,  and  the  wall  of  the 
thorax  expands  and  contracts  more  freely  for  being  partly 
cartilage.  It  is  by  this  expansion  and  contraction  that  we 
breathe.  Whoever  has  harnessed  horses  has 
noticed  that  they  generally  swell  their  chests, 
and  manifest  displeasure,  when  the  girths  are 
buckled  tight.  It  interferes  with  their  breath- 
ing, and  so  with  their  comfort.  If  we  are  wise 
we  shall  resist,  as  they  do,  any  compression  of 
our  chests  or  waists  by  tight  clothing.  The 
elastic  walls  readily  yield  to  pressure,  and  after 
a  time  become  permanently  misshapen.  The 
heart  and  lungs  are  then  crowded;  and  the 
liver  is  displaced,  and  encroaches  on  the  other 
organs.  Thus,  a  figure  is  acquired  which  is 
Fig.  6.  neither  beautiful  nor  healthful. 
THE  STEKNUM.  R  The  sternuiri)  or  breast-bone,  is  a  flat,  nar- 
row bone,  about  five  inches  long,  which  is  in  the  middle 
line  of  the  chest  in  front.  The  collar-bones  and  the  car- 
tilages of  the  rib?  are  joined  to  it. 


THE  BONES  AND  JOINTS. 


23 


6.  The  hyoid  bone  is  a  slender  bone  shaped  like  a 
horseshoe.  It  is  situated  in  the  neck  just  above  Adam's 
apple,  where  it  may  easily  be  felt.  The  base  of  the  tongue 
is  attached  to  it. 

BONES   OF   THE   UPPER  LIMB. 


Shoulder. 


Arm. 


SECTION  III. — 1.    The  upper  limb  is  divided  by  anat- 
omists into  shoulder,  arm,  fore-arm, 
and  hand.     In  ordinary  language, 
we  call  all   between  the  shoulder 
and  the  hand,  the  arm.     In  ana- 
tomical  language,  the  arm  extends  from 
shoulder  to  elbow;  the  fore-arm,  from  elbow 
to  hand. 

2.    The    bones         ,-,» 
of  the  shoulder  are 
the  clavicle,  or  col- 
lar-bone, and  the 
scapula,  or  shoul- 
der-blade.    The 
collar-bone     is 
about    as    large 
around  as  a  finger, 
and    curved     in 
shape.     It  extends 
from   the   upper  comer  of  the 
breast-bone    to     the     shoulder- 
blade.     It  braces  the  shoulder. 

3.  The  shoulder-blade  is  a 
flat,  three-cornered  bone,  with 
projections  extending  from  it,  to 
which  muscles  are  attached.  At  one  corner  is  a  smooth 


Hand. 


Fig.  7. 


Fig.  8. 

THE  SCAPULA.  —  1.  Processes.    2. 
Surface  for  shoulder  joint. 


24 


THE  HUMAN  BODY. 


surface  slightly  hollowed  out,  on  which  the  head  of  the 

arm-bone  plays. 

4.  The  arm-bone  is  called  the  humerus.  It  is  a  strong 
bone,  about  a  foot  long  in  a  grown  man.  It 
has  a  round  head,  which  plays  on  the  joint 
surface  in  the  shoulder-blade.  Its  lower  end 
is  joined  to  the  two  bones  of  the  fore-arm. 

5.  The  bones  of  the  fore-arm  are  called 
the  radius  and  the  ulna.  The 
radius  is  on  the  thumb  side, 
and  the  ulna  on  the  side  of 
the  little  finger.  The  radius 
is  joined  to  the  humerus  and 
to  the  ulna  in  such  a  way  that 
it  rolls  over  on  the  ulna,  and 
turns  the  palm  of  the  hand 
up  or  down.  The  ulna  is 
so  joined  to  the  humerus  that 
it  can  only  move  forward  and 
backward.  The  radius  is  joined 
closely  to  the  hand,  and,  when 
it  rolls  over  the  ulna,  carries 
the  hand  with  it. 

6.  The  hand  is  divided  into  the  carpus, 
or  wrist,  metacarpus,  or  palm,  and   pha- 
langes, or  fingers. 

7.  The  wrist  has  eight  short  bones,  irregu-   2'  TuE  ULNA* 
lar  in  size  and  shape.     These  are  bound  by  ligaments  into 
a   compact  bunch.     They  glide  a  little   on  each  other. 
Though   they  seem  to  be  put  together  without   design, 
they  are  really  shaped  and  joined  in  such  a  way  as  to 
give  freedom  of  movement  combined  with  strength. 


Fig.  9. 
THE  HUMERUS. 


Fig.  10. 
1.  THE  RADIUS. 


THE  BONES  AND  JOINTS. 


25 


8,  The  five  metacarpal  bones  are  slightly  curved,  so  as 
to  make  a  hollow  in  the  palm. 

The  phalanges  are  in  three  rows,  and  are  so  called  be- 
cause they  are  like  rows  of  soldiers 
(Greek,phalanx,8i  body  of  soldiers). 

The  thumb  stands  out  from  the 
rest,  and  can  be  made  to  meet  the 
end  of  each  of  the  fingers.  This 
enables  us  to  pick  up  and  handle 
small  things  with  great  delicacy. 
None  of  the  lower  animals  has  a 
thumb  like  man's  except  a  few  of 
the  apes,  and  theirs  is  not  so  per- 
fect for  handling.  It  is  his  hand 
more  than  any  other  part,  except 
the  brain,  that  gives  man  his  su- 
periority over  them.  Its  skill  and 
delicacy  when  trained  are  won- 
derful. Most  of  the  work  of  the 
world  is  done  in  part  with  the 
hand.  Very  much  of  it  could  not  be  done  at  all  if  man's 
hand  were  not  as  perfect  as  it  is. 

BONES   OF   THE   LOWER   LIMB. 

SECTION  IV.  —  1.  The  lower  limb  is  divided  into  hip, 
thigh,  leg,  and  foot.  In  ordinary  language,  the  word  leg 
means  the  lower  limb  from  hip  to  foot.  In  anatomical 
language,  the  part  between  the  hip  and  knee  is  called  the 
thigh  ;  the  part  between  the  knee  and  foot  is  the  leg. 

2.  The  hip-bone  is  so  irregular  in  shape,  that  the  old 
anatomists  could  not  think  of  any  name  that  suited  it; 
and  so  they  called  it  the  os  innominatum,  nameless  bone, 


Fig.  11. 

THE  HAND.  — 1.  Carpus, 
acarpus.    3.  Phalanges. 


I.  Met- 


THE  HUMAN  BODY. 


The  two  hip-bones  come   together  in  front.      Behind 
they  are  separated  by  the  sacrum.     The  cavity  inclosed 
between  them  is  the  pelvis,  or  basin. 

3,  The  femur,  or  thigh-bone,  is  the 
longest  bone  in  the  body. 
It  has  a  round  head,  which 
fits  into  a  socket  in  the  hip- 
bone. At  its  lower  end  it 
spreads  cut  to  make  a  broad 
surface  for  the  knee-joint. 
It  is  slightly  curved. 


Leg. 


Fig.   14. 
THE  PATELLA. 


Fig.  12. 
THE  LOWER  LIMB. 


Fig.  13. 
THE  FEMUR. 


4.  In  front  of  the  knee  is 
a  small  bone,  heart-shaped, 
which  is  called  the  patella, 
or  knee-pan. 

5.  The  leg  has  two  bones, 

the  tibia  (Latin,  tibia,  a  flute)  and  the  fibula  (Latin,  fibula, 
a  shawl-pin).  The  tibia  is  a  strong  bone.  It  has  a  sharp 
ridge  in  front,  which  is  called  the  shin.  The  tibia  is 
joined  to  the  femur  above.  The  fibula  is  a  long,  slender 
bone.  It  is  joined  to  the  tibia  above  and  below.  The 
lower  ends  of  these  two  bones  are  joined  to  the  ankle- 


THE  BONES  AND  JOINTS. 


27 


Tarsus. 


bone  of  the  foot.      They  can  easily  be  felt,  one  on   the 
inner,  the  other  on  the  outer,  side  of  the  ankle. 

6,  The  foot  consists  of  tarsus,  metatarsus, 
and  phalanges. 

7,  There  are  seven  irregular  bones  in  the 
tarsus.     They  form  the  ankle,  the  heel,  and 
the  instep. 

The  metatarsal  bones  form  the  "flat"  of 
the  foot,  and  part  of 
the  instep.  There  are 
five  in  each  foot. 

The  phalanges, 
fourteen  in  each  foot, 
form  the  toes. 

8.  The  bony  struc- 
ture of  the  foot  is  quite 
like  that  of  the  hand. 
The  differences  are 
such  as  fit  it  for  its 
humbler  work .  Its 
inner  side  is  arched, 
and  the  weight  rests 
on  the  heel  and  the 
ball  of  the  toe.  The 
foot  is  strong  and  elastic,  and  should 
be  dressed  in  such  a  way  as  not  to 
distort  its  shape  or  check  its  move- 
ment. But,  while  we  wonder  at  and  despise  the  Chinese 
practice  in  this  regard,  we  treat  our  feet  in  ways  as  truly 
unreasonable.  The  shape  of  our  shoes  is  determined,  not 
by  the  design  of  Nature,  but  by  fashion.  They  are  often 
Almost  always  they  are  too  short,  and  too  nar- 


Fig.  15. 

1.  THE    TIBIA. 
2.  THE  FIBULA. 


Fig.  16. 
BONES  or  THE  FOOT. 


too  tight. 


28  THE  HUMAN  BODY. 

row  across  the  toes.  Consequently  the  toes  of  most  grown 
people  are  squeezed  together,  frequently  overlapping. 
The  great  toe  naturally  rests  a  little  separated  from  its 
neighbor,  and  almost  in  a  straight  line  with  the  inner 
side  of  the  foot.  If  we  make  it  turn  in,  its  principal  joint 
stands  out  prominent,  and  from  the  pressure  becomes 
inflamed.  A  bunion  is  formed  there.  A  corn  is  another 
painful  result  of  pressure. 

The  foot  is  a  much-enduring  member,  and  is  useful, 
even  though  crippled.  But  grace  and  ease  of  movement 
are  constantly  sacrificed,  and  numberless  miseries  in- 
curred, for  the  sake  of  making  the  foot  look  small. 

Athletes  and  pedestrians  long  ago  discovered  the  neces- 
sity of  a  shoe  which  gives  freedom  to  the  foot.  Such  a 
shoe  is  never  tight.  The  heel  (if  any)  is  low  and  broad, 
and  directly  under  the  heel  of  the  foot.  The  sole  is  as 
broad  as  the  foot  itself,  and  at  least  half  an  inch  longer. 

STRUCTURE   OF   BONE. 

SECTION  V.  —  1,  If  we  saw  a  long  bone  in  two  length- 
wise two  things  are  noticeable:  — 


Fig.  17. 
SECTION  OF  THE  FKMUK. 


1.  Its  shaft  is  hollow.     During  life  the  cavity  is  filled 
with    marrow.     This   consists  largely   of  fat,  and   is  a 


THE  J1ONE8  AND  JOINTS.  29 

store  of  nourishment  which  helps  to  sustain  the  body 
when  it  is  deprived  of  food.  It  has  been  proved  by 
experiment,  that  a  hollow  shaft  is  stronger  than  a 
solid  shaft  of  the  same  material  and  the  same  weight  and 
length. 

2.  The  bony  substance  of  the  shaft  is  hard  and  com- 
pact. The  large  ends,  on  the  contrary,  though  they  are 
not  hollow,  are  filled  with  cells,  and  present  a  honey- 
combed appearance.  It  is  desirable  that  the  shaft  should 
be  slender  and  strong.  Its  substance  is,  therefore,  very 
compact.  It  is  desirable  that  the  ends  should  be  large, 
to  give  a  broad  surface  for  the  joints.  Their  substance  is, 
therefore,  open.  If  it  were  compact,  it  would  increase  the 
weight  unnecessarily. 

2,  If  we  saw  a  flat  bone  in  two,  as  one  of  the  bones  of 
the  skull,  or  a  short  bone  as  one  of  the  bones  of  the  wrist, 
we   shall   find,  that, 

while  its  shell  is  of 
compact  tissue,  its  in- 
side is  of  the  same 
honeycombed  tissue 
that  we  found  in  the  ***'  18' 

I.  THE  PERIOSTEUM. 

ends  of  the  long  bone. 

3.  Bones    are    well    supplied    with    blood-vessels    and 
nerves.     We  can  find  in  every  bone  one  or  more  holes 
through  which  a  small  blood-vessel  passes  to  the  interior. 
A  living  bone  is  covered  with  a  membrane  called  the  peri- 
osteum.    In  this  membrane  is  a  fine  net- work  of  blood- 
vessels, from  which  a  countless  number  of  little  vessels 
pass  directly  into  canals  in  the  bone.     These  are  called 
Haversian  canals.     They  run  through  every  part  of  the 
bone. 


30  THE  HUMAN   HODY. 

CHEMICAL,    COMPOSITION    OF    BONE. 

SECTION  VI.  —  1,  Bone  is  about  two-thirds  mineral,  and 
one-third  animal,  matter.  The  mineral  matter  is  chiefly 
phosphate  of  lime.  This  substance  makes  more  than  half 
of  the  bone.  The  mineral  and  animal  matter  are  closely 
combined,  but  they  can  be  separated  in  two  ways:  — 

1.  If  we  put  a  bone  in  a  moderate  fire,  and  burn  it,  it 
will  become  porous  and  brittle,  but  will  retain  its  shape. 
The  animal  matter  is  burned  out,  but  the  mineral  remains. 

2.  If  we  put  a  bone  in  weak  hydrochloric  acid,  and  allow 
it  to  remain  for  a  few  weeks,  it  will  become  as  pliable  as  a 
rope,  and  can  be  tied  in  a  knot.     The  acid  has  eaten  out 
all  the  mineral  matter,  but  has  left  the  animal  matter. 
If  a   bone   has   too  much  mineral  matter,  it  is  brittle. 
This  is  the  condition  of  the  bones  of  old  people,  and  some- 
times of  younger 
persons.     They 
break  very  easily. 
In   the   bones  of 
children,   on    the 
other    hand,   the 
animal  matter  is 
abundant;  and 
they  will  bend  a 

-  id.  good  deal   before 

A  BONE  AFTER   SOAKING   IN   HYDROCHLORIC   ACID.  flipv      }vrp"")lv  Til 

the  disease  of  children  called  rickets,  there  is  so  little 
mineral  matter  in  the  bones,  that  they  are  too  soft.  The 
legs  become  bowed,  the  head  enlarges,  and  the  whole 
frame  gets  out  of  shape. 

2,    During  childhood  and  youth  the  skeleton  is  assum- 


THE  HONES  AND  JOINTS. 


31 


ing  the  form  which  it  is  to  keep  through  life.  It  is  pliahle, 
and  may  be  molded  to  healthfulness  and  grace,  or  to 
deformity.  Nature  should  be  allowed  to  shape  it  in  her 
own  way,  and  all  habits  of  dress  or  attitude  or  movement 
that  interfere  with  the  natural  outlines  should  be  care- 
fully avoided. 

THE   JOINTS. 

SECTION  VII. — 1,    The  joints  of  the  body  with  which 
we  are  most  familiar  are  movable ;  but  most  of  the  joints 
of  the  head-bones  are  like  a 
joint   in    a    table   or   chair. 
They  are  fixed. 

The  joints  between  the 
bodies  of  the  vertebrse  have 
a  little  motion,  but  are  not 
freely  movable  like  the  joints 
of  the  limbs. 

There  are,  then,  in  the 
body,— 

Immovable  joints. 

Slightly  movable  joints. 

Fredy  movable  joints. 

2.  The  movable  joints  are 
of  various  kinds.  Sometimes  JOINT9  op  f  _  t  Fronla| 

the  tWO  Surfaces  Only  glide  a      bone.      2.    Parietal    bone.      3.    Occipital 

little  on  each  other,  as  in  the 

wrist.     Sometimes  one   bone   moves   on  another,  like   a 

door  on  its  hinge.      The  elbow  and  the  ankle  are  of  this 

kind. 

Sometimes  a  round  bone  fits  into  a  round  socket,  and 
moves  in  all  directions.     The  hip-joint  is  of  this  kind 


32 


THE  HUMAN  BODY. 


Inuominate. 


PARTS   WHICH   COMPOSE   A   JOINT. 

3.  In  a  joint  there  are  — 

L   Tivo  or  more  bones,  each  covered,  where  they  come 

in  contact,  with  a  thin, 
smooth  layer  of  cartilage 
or  gristle.  Cartilage  is 
more  elastic  than  bone, 
and  serves  as  a  spring 
in  the  joint. 

2.  Ligaments  which 
bind  the  ends  of  the 
bones  firmly  together. 
A  ligament  is  a  white, 
glistening  band,  very 
strong,  and  generally 
not  elastic.  When  we 
examine  it  with  a  mi- 
croscope, we  find  that  it 
is  made  of  fine  white 
fibers,  lying  side  by  side 

like  the  threads  of  a   ribbon,  only  there  are  no   cross- 
fibers.     They  all  run  lengthwise. 

3.  The  cavity  of  the  joint  has  a  thin  lining,  called  a 
synovial  membrane.  This  membrane  gives  out  a  fluid 
called  syncJvia,  or  joint-water.  This  serves  the  same  pur- 
pose that  the  oil  we  put  in  the  joints  of  machinery  serves. 
But  while  these  need  constant  attention,  and  soon  wear 
out,  the  living  joint  oils  itself,  and  may  be  in  constant 
use  for  seventy  years  or  more  without  causing  a  thought 
in  the  mind  of  its  owner. 

If,   however,  joints   become    diseased,  they  are  very 


Femur , 

Fig.  21. 
THE  HIP-JOIXT. 


THE  BONES  AND  JOINTS. 


33 


painful.     They  sometimes  become  enlarged  and  stiff  and 
misshapen. 

4,  The  joints  of  young  chil- 
dren bend  very  freely:  as  they 
grow  older,  they  become  less 
flexible.      Some  have  "looser" 
joints  than  others.     Those  pub- 
lic performers  who   can  twist 
themselves    into    marvelous 
shapes,  are  persons,  who,  by  a 
course  of  training  begun  early 
in  life,  have  gradually  stretched 
their  ligaments. 

5,  Ligaments  are  tough,  and 
not  easily  hurt;   but  when  we 
do  "sprain"  a  joint,  which 
means  that  we  have  torn  or 
overstretched  its  ligaments,  they  recover  slowly. 

GROWTH    OF    BONES. 

SECTION  VIII.  —  1.  Bone,  though  it  is  so  firm  and 
hard,  is  all  the  time  wasting  and  being  repaired,  like  the 
soft  parts.  If  madder,  which  is  of  a  bright  red  color,  is 
mixed  with  the  food  of  animals,  their  bones  will  soon 
become  dyed  with  it.  This  shows  that  the  madder  has 
passed  into  the  bones.  After  the  madder  is  stopped,  the 
bones  lose  the  red  color.  This  shows  that  the  madder 
has  passed  out.  It  is  reasonable  to  conclude  that  nour- 
ishing matter  passes  in  with  the  madder,  and  that  waste 
matter  passes  out  as  in  other  tissues. 

It  is  therefore  important  for  the  growth  of  the  bony 
frame  to  keep  the  blood  pure. 


Fig.  22. 
THE  SHOULDER-JOINT. 


34  THE    HUMAN    BODY. 

2,  The  common  belief  that  the  growth  of  the  frame  of 
an  animal  or  of  a  child  may  be  checked  by  alcohol  or 
tobacco  is  reasonable. 

3,  Drunkenness  in  parents  is  one  of  the  causes  of  the 
bone-diseases  which  deform  scrofulous  children. 


QUESTIONS. 

SECTION  I.  —  1.  What  is  the  skeleton  ?  What  three  purposes  does 
it  serve?  Can  an  animal  body  destitute  of  bones  move?  If  so,  in 
what  way  ? 

2.  What  are  the  two  main  cavities  formed  by  the  skeleton? 
How  are  the  skull  and  backbone  especially  fitted  to  protect  their 
contents  ?    What  are  the  two  main  divisions  of  the  cavity  of  the 
trunk  ?    What  is  that  portion  of  the  lower  division  which  is  between 
the  hip-bones  called?    What  is  the  name  of  the  partition  between 
chest  and  abdomen?    Is  there  any  partition  between  abdomen  and 
pelvis ?    What  are  the  bony  walls  of  the  chest?    What  are  its  prin- 
cipal contents  ?    Why  is  not  the  abdomen  as  well  walled  as  the 
thorax  ? 

3.  How  many  bones  are  there  in  the  body  ?    In  the  spinal  column  ? 
In  the  head?    In  the  trunk?    In  the  upper  limbs?    In  the  lower 
limbs? 

SECTION  II.  —  1.  What  bones  of  the  skull  are  movable?  What 
organs  of  special  sense  are  guarded  by  the  bones  of  the  skull  ? 

2.  What  is  the  structure  of  a  vertebra  ?    What  is  a  process  on  a 
bone?    What  canal  do  the  vertebrae  make  when  they  are  joined? 
With  what  cavity  is  this  canal  continuous  ?    What  springs  are 
found  in  the  spinal  column?    What  is  the  position  of  the  sacrum  ? 
Of  the  coccyx  ? 

3.  What  is  the  shape  of  a  baby's  spine?    What  are  the  natural 
curves  of  the  back  ?    What  curves  are  unnatural  ?    What  is  the 
harm  of  a  stoop  ?    What  are  the  causes  of  unnatural  curves  in  the 
backbone? 

4.  How  are  the  first  seven  ribs  distinguished  from  the  last  five? 


THE    BONES    AND    JOINTS.  35 

Which  are  called  floating-ribs?  What  are  the  costal  cartilages? 
What  is  their  use  ?  What  are  the  effects  of  compressing  the  chest 
and  waist  ? 

5,  Describe  the  sternum? 

6,  Where  is  the  hyoid  bone  situated  ?  and  what  important  organ 
is  attached  to  it  ? 

SECTION  III.  —  1,  What  are  the  divisions  of  the  upper  limb  ? 

2,  What  is  the  common  name  of  the  clavicle?    What  is  its 
situation  ? 

3,  What  is  the  common  name  of  the  scapula?    What  is  its 
situation  ? 

4,  Name  the  arm-bone. 

5,  What  are  the  bones  of  the  fore-arm  ?    Which  rolls  over  the 
other  ?    Which  is  most  closely  connected  with  the  hand  ? 

6,  What  are  the  divisions  of  the  hand  ? 

7,  How  many  bones  in  the  carpus  ? 

8,  How  many  bones  in  the  metacarpus  ?    How  many  phalanges  ? 
What  in  the  human  hand  especially  gives  it  an  advantage  over  the 
hands  and  paws  of  lower  animals? 

SECTION  IV.  —  1.  What  are  the  divisions  of  the  lower  limbs? 

2,  Why  is  the  hip-bone  called  the  os  innominatum  ? 

3,  What  is  the  longest  bone  in  the  body  ? 
4  Where  is  the  patella  situated  ? 

5,  Name  the  leg-bones.    What  is  the  shin?    What  is  the  use  of 
the  fibula? 

6,  What  are  the  divisions  of  the  foot  ? 

7,  How  many  bones  in  the  tarsus?    In  the  metatarsus?    How 
many  phalanges  ? 

8,  What  is  the  effect  of  wearing  too  tight  shoes  ?    Of  having  a 
high  heel  under  the  middle  of  the  foot?    What  is  the  natural 
direction  of  the  great  toe  ?    What  is  the  proper  shape  for  a  shoe  ? 

SECTION  V.  —  1.  Is  a  bone  solid  all  through  ?  What  part  is  hol- 
low ?  What  part  is  filled  with  thin-walled  cells  ?  What  is  contained 
in  the  cavity  ?  Why  is  it  hollow  ?  Why  are  the  ends  of  the  long 
bones  enlarged? 

2,  What  is  the  structure  of  a  short  bone  ? 


36  THE    HUMAN    BODY. 

3,  How  do  blood-vessels  and  nerves  get  into  a  bone  ?  What  are 
the  Haversian  canals  ? 

SECTION  VI.  —  1.  What  is  the  chemical  composition  of  bone? 
How  can  the  animal  and  mineral  constituents  be  separated?  Why 
do  the  bones  of  old  people  break  more  easily  than  children's  ? 

SECTION  VII.  —  1-  What  three  kinds  of  joints  are  there  in  the 
body? 

2,  Of  the  movable  joints,  what  varieties  are  there? 

3,  What  are  the  essential  parts  of  a  joint?    How  does  a  joint 
oil  itself? 

4,  Why  are  some  people's  joints  looser  than  those  of  other 
people  ? 

5,  What  is  a  sprain  ? 

SECTION  VIII.  —  1.  Are  bones  constantly  changing,  like  other 
tissues  ? 

2.  What  helps,  and  what  may  hinder,  their  growth  ? 


THE  FIOURE  ON  THE  OPPOSITE   PAGE  GIVES  A  GENERAL  REPRESENTATION  OF 
THE   MUSCULAR  SYSTEM. 


40  THE  HUMAN  ]30DT. 


CHAPTER  III. 
THE    MUSCLES. 

SECTION  I. — 1,  The  muscles  are  organs  of  motion. 
They  cover  the  bones,  and  constitute  the  "  flesh."  They 
are  found  also  in  the  walls  of  the  alimentary  canal,  and 
of  the  blood-vessels,  and  in  other  inward  parts.  The  heart 
is  chiefly  muscle. 

2,  The  muscles  with  which  we  are  most  familiar,  act 
when  we  mil  that  they  shall  act.     We  can  walk,  run,  or 
sit  still;  we  can  move  our  arms  or  our  heads  as  we  will; 
but  we  can  not  stop  the  beating  of  our  hearts  in  this  way. 
The  movements  of  the  intestines  are  also  independent  of 
our  will. 

3,  Muscles  are  accordingly  divided  into  two  classes, — 
voluntary,  or  those  which  are  subject  to  the  will;   and 
involuntary,  or  those  which  are  not  subject  to  the  will. 

4,  The  voluntary  muscles  constitute  about  two-fifths  of 
the  weight  of  the  body.     They  are  compactly  arranged 
over  the  skeleton,  most  of  them  being  attached  to  a  bone 

SUGGESTIONS  TO  TEACHERS.  —  1.  A  piece  of  fresli  beef  will  illustrate  to 
the  naked  eye  the  gross  structure  of  voluntary  muscle.  With  a  micro 
scope  magnifying  four  hundred  times,  a  small  fragment  teased  out  with 
a  needle  will  show  the  structure  of  the  fibers.  The  play  of  the  muscles 
and  tendons  in  the  fore-arm  is  easily  seen  in  a  thin  person.  The  action  of 
involuntary  muscle  can  be  seen  in  the  iris,  whose  muscular  fibers  contract 
under  the  influence  of  light,  but  are  not  subject  to  the  will. 

2.  Fibrous  tissue  is  seen  between  the  muscular  bundles  of  beef.  Ten- 
dons show  in  the  leg  of  a  fowl. 


THE  MUSCLES. 


41 


at  each  end.  They  are  of  various  shapes,  according  .to 
their  position  and  use.  Some  are  long,  some  short :  some 
are  round,  and  some  flat.  In  the  living  body,  all  the 
muscles  of  a  limb  are  bound  together 
and  covered  by  fibrous  tissue. 

5.  Voluntary  muscles  are  commonly 
attached  to  a  bone,  at  one  or  both  ends, 
by  means  of  a  tendon  or  aponeurosis. 
A  tendon  is  a  glistening  cord  of  fibrous 
tissue.    It  is  tough,  and  does  not  stretch. 
An  aponeurosis  differs  from  a  tendon 
in  being  flat.     If  the  muscle  is  flat,  it 
ends  in  an  aponeurosis :  if  it  is  round, 
it  tapers  down  to  a  tendon. 

6,  There  are  more  than  five  hun- 
dred muscles  in  the  body.     Most  of 
them  are  in  pairs,  the  two  sides  of  the 
body  being  alike.     The  smallest  is  the 
stapedius,  a  muscle  in  the  ear,  which 
is  only  one-sixth  of  an  inch  in  length : 
the  longest  is  the  sartorius,  which  ex- 
tends from  the  hip  to  the  leg  below 
the  knee,  and  is  over  eighteen  inches 
in  length. 

The  biceps  of  the  arm  has  two  heads, 
both  arising  from  the  shoulder-blade, 
and  is  inserted  into  the  radius  just  below  the  elbow. 
The  great  muscles  which  pass  from  the  breast-bone  to 
the  upper  end  of  the  arm  are  called  pectorals.  The 
gastrocnemius  constitutes  a  large  part  of  the  calf  of  the 
leg.  Its  tendon,  called  the  tendon  of  Achilles,  is  inserted 
into  the  heel,  and  is  the  largest  tendon  in  the  body. 


42  THE  HUMAN  BODY. 


PROPERTIES   OP    MUSCLE. 

SECTION  II. — 1,  Muscle  has  a  peculiar  power  of  short- 
ening itself.  There  is  a  kind  of  elastic  tissue  in  the  body, 
of  which  a  few  ligaments  are  made,  which,  like  rubber, 
will  contract  after  it  has  been  stretched ;  but  muscle  is 
the  only  tissue  that  contracts  without  being  stretched 
first.  When  a  muscle  grows  shorter,  it  grows  thicker  at 
the  same  time,  just  as  the  body  of  a  worm  will  shorten 
and  thicken.  If,  for  example,  I  place  my  left  hand  on 
the  biceps  of  my  right  arm,  and  then  bend  my  elbow,  I 
shall  feel  the  biceps  swelling,  and  growing  hard :  at  the 


Fig.  24. 

1.  BICEPS  MUSCLE.    The  dotted  lines  indicate  the  changed  shape  of  the  biceps  when 
the  fore-arm  is  drawn  up. 

same  time  it  has  shortened,  and  thus  drawn  the  bone 
to  which  it  is  attached  up  toward  the  shoulder.     We  do 
not  understand  how  it  is  that  muscle  contracts  when  we 
will  that  it  shall.     We  can  only  say  that  it  does  so. 
2,    Involuntary  muscle  has  the  same  power  of  shorten- 


THE  MUSCLES. 


43 


ing  that  voluntary  muscle  has.  But  it  will  not  do  this  in 
obedience  to  the  will.  Cold  contracts,  and  heat  relaxes  it. 
The  involuntary  muscle  in  the  walls  of  the  intestine  con- 
tracts when  food  comes  in  contact  with  it.  Many  other 
influences  produce  the  same  effect,  but  the  will  which 
controls  the  voluntary  muscle  has  no  authority  over  the 
involuntary.  Involuntary  muscle  never  contracts  as  rap- 
idly as  voluntary  muscle  sometimes  does.  It  moves  in  a 
sluggish  way. 

STRUCTURE  OF   MUSCLE. 

SECTION  III. — 1,    If  we  examine  a  little  shred  of  vol- 
untary muscle  with  a  microscope  which 

will  magnify  four  hundred 

times,  we  shall  see  that  the 

small  fibers  which  are  visi- 
ble to  the  naked   eye   are 

made  up  of  still  smaller 

libers,  and  that  these  have 

dark   lines    crossing    them. 

These  microscopic  fibers  are 
gathered  into  bundles,  and  these  again 
into  larger  bundles.      The  muscle  is 
made  up  of  many  such  bundles,  sur- 
rounded and  bound  together  by  fibrous 
membranes.     We  can  readily  see  this 
in  a  piece  of  beef.     The  fibers  con- 
stitute what  we  call  the  grain  of  the 
meat.  ***• 26- 

T  FIBERS  or  INVOLUNTART 

2,    Involuntary  muscle,  when  ex-    MUSCLE. -i.  Fiber  soaked  iu 
amined  with   a  microscope,  is  also    aceticacid-  2.  Nucleus, 
seen  to  consist  of  fibers.     But  they  are  much  shorter  than 


E" 
55 

a 


1 


44  THE  HUMAN   BODY. 

the  fibers  of  voluntary  muscle;  and  they  are  broad  in  the 
middle,  and  taper  to  each  end.  They  have  no  cross-stripes, 
and  have  a  spot  in  the  center  called  a  nucleus. 

MUSCULAR    EXERCISE. 

SECTION  IV. — 1,  It  is  a  law  of  Nature,  that  every  liv- 
ing thing,  in  order  to  remain  in  health,  must  do  the  thing 
that  it  was  made  to  do.  A  stone  was  made  to  lie  inactive 
and  motionless.  Men,  as  well  as  the  lower  animals,  were 
nmde  for  activity  and  motion.  Every  part  of  the  body 
must  do  the  work  that  it  was  made  to  do.  The  muscles 
must  move,  the  stomach  must  digest,  the  nerves  must  be 
in  use,  the  brain  must  think.  The  part  which  is  allowed 
to  remain  inactive  becomes  unhealthy  and  weak.  This  is 
the  great  law  of  exercise. 

2,  This  law  applies  especially  to  young  persons.     After 
the  body  has  got  its  growth,  and  has  become  firm  and 
strong,  it  can  endure  bad  usage  or  neglect  better  than  in 
the  growing  period. 

3,  Some  people  are  engaged  in  occupations  which  give 
abundant  exercise  to  all  the  organs  of  body  and  mind. 
Such  occupations  tend  to  long  life.     Statistics  kept  in  the 
State  of  Massachusetts  for  thirty  years,  of  the  length  of 
life  in  different  occupations,  showed  that  the  farmers  lived 
the  longest. 

4,  Many  employments  require  the  use  of  the  muscles 
more  than  of  the  brain.     Persons  engaged  in  such  em- 
ployments should,  during  their  hours  of  recreation,  exer- 
cise their  minds. 

5,  Other  occupations  engage  the  mind  while  the  body 
is   inactive.      Those  who  have  such  occupations  should 
seek  recreation  in  muscular  exercise. 


TUE  MUSCLES.  45 


6,  It  is  especially  important  that  the  muscles  should  be 
exercised,  for  several  reasons. 

1.  Because  they  are  so  large  a  part  of  the  body.     Nearly 
one-half  the  weight  of  a  man  is  muscle. 

2.  Because  they  are  made  capable  of  great   activity. 
They  are  abundantly  supplied  with  blood-vessels,  and  the 
current  of  blood  should  flow  freely  through  them.     When 
they  are  idle,  its  flow  is  sluggish. 

3.  Because,  when  the  muscles  are  exercised,  all  other 
parts  of  the  body  are  refreshed.     We  may  exercise  the 
brain  vigorously  while  the   muscles  are  quite  idle,  and 
the  blood  circulates  no  faster.     But,  when  we  exercise  the 
muscles,  the  heart  beats  more  strongly,  and  the  blood 
flows  more  rapidly,  not  only  through  the  muscles,  but 
also  through  the  skin,  the  liver,  the  stomach,  the  brain. 
The  organs  which  remove  waste  matters  from  the  blood 
are  more  active,  and  the  whole  body  is  purified.     Exercise 
is  Nature's  stimulant. 

7,  Muscular  exercise  is  valuable,  not  only  because  it 
promotes  the  general  health,  but  also  because  it  directly 
improves  the  muscular  system.    A  strong  and  well-shaped 
body  is  to  be  desired.     The  ancient  Greeks,  who  for  their 
physical  beauty  and  vigor,  and  their  intellectual  power, 
have  been  the  admiration  of  all  succeeding  nations,  made 
very  much   of  the   cultivation  of  the  muscles.      Their 
scholars  and   statesmen  were  proud   if  they  could  win 
prizes  in  the  great  athletic  games.     Much  of  the  work  of 
life  is  done  by  the  muscles.     It  will  be  better  done  if  they 
are  strong  and  well  trained. 

8,  Three  things  are  to  be  sought  in  the  training  of  the 
muscles,  —  1.  Strength,  2.  Alertness,  3.  Endurance. 

i.  Strength.  The  muscles  increase  in  size  and  power  by 


46  THE  HUMAN  13ODY. 

use.  It  is  important  that  this  increase  should  be  uniform. 
Exercises  should  be  chosen  with  reference  to  the  develop- 
ment of  arms,  legs,  and  trunk.  It  is  a  common  mistake, 
to  regard  strength  as  the  only  end  of  muscular  exercise. 
A  man  is  not  required  to  do  the  work  of  a  horse.  Great 
strength  does  not  always  imply  good  health.  Athletes 
are  sometimes  overtrained,  so  that  their  health  is  impaired 
while  their  muscles  are  large.  Prize-fighters  frequently 
die  early. 

s.  Alertness.  This  is  the  power  to  obey  quickly  the 
commands  of  the  will  or  the  impulse  of  the  senses.  In 
many  trades,  and  some  professions,  it  is  of  the  utmost 
value.  Games  which  require  keen  watching  and  rapid 
movements  develop  it. 

s.  Endurance.  This  is  the  power  of  continuing  to  make 
efforts  for  a  long  time  without  tiring  out.  It  is  not  always 
the  largest  muscle  that  has  the  most  of  this  quality.  This, 
with  healthy  action  of  other  organs,  constitutes  what  is 
called  "  staying  power,"  and  gives  the  victory  in  a  long 
race.  It  is  acquired  by  regular  exercise. 

9,  Muscular  exercises  are  valuable,  also,  because  they 
commonly  train   the  eye  and   the  ear  to  quickness  of 
perception. 

10,  The  muscles  are  larger  and  firmer  in  men  than  in 
women.     Nevertheless,  the  need  of  muscular  exercise  is 
just  as  real  for  one  sex  as  for  the  other.     It  is  as  truly 
requisite  for  their  health  and    proper  growth.     Neither 
unsuitable  dress,  nor  false  ideas  of  propriety,  should  be 
allowed  to  deprive  them  of  it. 

11,  Exercise,  to  be  most  useful,  should  be  regular.     To 
take  several  hours  of  it  to-day,  and  none  to-morrow,  is 
less  beneficial  than  to  take  a  moderate  amount  daily.     It 


77/7?   MUSCLES.  47 


should  be  taken,  if  possible,  out  of  doors.     Much  of  its 
benefit  comes  from  breathing  a  great  deal  of  pure  air. 

The  more  heartily  the  mind  is  interested  and  engaged, 
the  more  the  benefit. 

12,  Violent  exercise  should  not  be  taken  directly  after  a 
full  meal.     At  this  time  the  stomach  has  work  to  do.     If 
the  blood  is  drawn  away  from  it  to  the  muscles,  and  all 
the  strength  is  engaged  in  muscular  efforts,  the  digestion 
will  be  checked.     If  such  a  practice  be  long  continued, 
the  stomach  will  be  weakened. 

13,  In  muscular  exercise,  as  in  every  thing  else,  it  is 
important  to  avoid  excess.    It  is  excess  to  exercise  so  long 
or  severely  as  to  be  unfitted  for  other  occupations.     It  is 
excess  to  exercise  until  a  muscle  or  limb  is  painfully  ex- 
hausted, and  does  not  soon  rest.     It  is  excess  to  attempt 
through  ambition  exercises  that  are  beyond  the  strength. 
It  is  excess  to  engage  in  severe  exercises  when  exhausted 
by  mental  or  other  labor. 

Excessive  exercise  sometimes  results  in  bleeding  from 
the  lungs,  sometimes  in  enlargement  of  the  heart.  That 
organ,  being  compelled  to  overwork,  becomes  too  large; 
and  this  causes  illness,  and  sometimes  death. 

14,  There  are  many  small  muscles  in  the  face,  which 
are  attached  by  one  end  to  the  bone,  by  the  other  to  the 
skin.     By  acting  together,  they  give  a  great  variety  of 
expression.     The   thoughts    and    feelings    are  indicated. 
Grief  causes  one  set  of  muscles  to  contract,  joy  another. 
So  naturally  is  the  action  of  particular  muscles  associated 
with  certain  emotions,  that  it  is  difficult  for  most  people 
to  conceal  their  feelings  from  one  who  is  steadfastly  ob- 
serving the  countenance.     The  faces  of  the  lower  animals 
are  not  as  well  supplied  with  muscles,  nor  are  they  as  soft 


48  THE  HUMAN  BODY. 

and  movable  as  the  human  face.  They  express  only  a 
limited  number  of  thoughts  and  feelings.  The  face  of 
the  lion  expresses  dignity;  that  of  the  tiger,  cruelty;  that 
of  the  ox,  patience.  The  expressions  which  are  most  fre- 
quently on  the  face  become  after  a  time  permanent :  thus 
the  character  is  written  on  the  countenance.  A  sullen  or 
bitter  temper  makes  an  unpleasing  aspect.  A  genial  and 
kindly  disposition  will  in  time  impart  its  own  beauty  to 
the  face. 

EFFECT   OF  ALCOHOL   AND   TOBACCO. 

SECTION  V.  —  1.  By  the  action  of  alcohol,  muscle  is 
sometimes  changed,  in  part,  to  fat.  It  thus  becomes 
flabby  and  feeble. 

Alcohol  affects  the  muscles  indirectly,  by  affecting 
the  digestion  and  the  blood,  and  so  spoiling  their  nour- 
ishment. 

The  athlete  training  for  a  prize,  knows  well,  that,  if  he 
indulges  freely  in  alcoholic  drinks,  he  will  surely  fail  to 
bring  his  muscles  to  a  hard  and  vigorous  condition. 
Total  abstinence  from  alcohol  and  tobacco  is  important 
for  his  success. 

2,  Firm  and  active  muscles  are  desirable  for  every  one. 
The  boy  who  thinks  it  manly  to  smoke,  is,  by  doing  so, 
lessening  that  muscular  power  which  is  an  admirable  and 
manly  possession.  The  pale  faces,  dull  eyes,  and  flabby 
limbs  which  this  practice  tends  to  produce,  give  no  sign 
of  manliness. 

It  is  true  that  men  distinguished  for  strength  of  body 
are  often  users  of  intoxicating  drinks  or  tobacco.  But 
it  is  also  true  that  such  men  frequently  become  diseased, 


THE    MUSCLES.  49 


and  die  before  their  time.     They  have  squandered  the 
powers  which  nature  has  given  them. 

QUESTIONS. 

SECTION  I.  —  1.  What  are  muscles?    Where  are  they  found? 
2,  3,  What  two  kinds  of  muscles  are  there  ? 

4,  What  holds  the  muscles  together  ? 

5,  What  is  a  tendon  ?    An  aponeurosis  ? 

6,  How  many  muscles  in  the  body?     Which  is  the  longest? 
Which  is  the  smallest?    Where  is  the  biceps  humeri?    Pectoral? 
Gastrocnemius  ?    Tendon  of  Achilles  ? 

SECTION  II.  —  1.  What  is  the  special  property  of  muscle  ?  Can 
we  explain  the  contraction  of  muscle? 

2,  What  is  the  difference  between  the  contraction  of  voluntary 
and  involuntary  muscle  ? 

SECTION  III. — 1.  How  does  voluntary  muscle  look  under  the 
microscope  ? 

2,  How  does  involuntary  muscle  look  under  the  microscope? 

SECTION  IV. — 1.  What  is  the  law  of  exercise? 

2.  Is  exercise  more  important  for  young  than  for  older  persons  ? 

3.  What  class  of  people  have  the  best  prospect  of  long  life  ? 

4.  5,  What  kind  of  exercise  is  best  suited  to  a  muscle-worker? 
What  kind  to  a  brain-worker? 

6,  What  three  general  reasons  are  there  for  muscular  exercise? 

7,  What  special  reasons  ? 

8,  What  three  qualities  of  muscle  should  be  cultivated? 

11.  Name  the  conditions  which  make  exercise  useful. 

12,  Name  the  cautions  to  be  observed  in  exercise. 

13,  What  is  excess  in  exercise  ?    What  are  its  results  ? 

14.  What  is  the  use  of  the  muscles  of  the  face?    How  is  char- 
acter written  on  the  countenance  ? 

SECTION  V.  —  1.  What  change  can  alcohol  make  in  muscle? 
How  does  it  affect  the  muscles  indirectly?  What  is  the  practice 
of  athletes  in  training  with  regard  to  alcohol  and  tobacco? 


50  77/1?   HUMAN  BODY. 


CHAPTER  IV. 
WORK    AND    WASTE —THE     BLOOD. 

SECTION  I.  —  1.  The  body,  like  not-living  machines, 
tends  to  wear  out  by  use.  Even  the  enamel  of  the  teeth, 
which  is  the  hardest  substance  found  in  it,  at  length  gives 
way. 

2.  The  soft  parts  wear  out  very  rapidly.     In   every 
movement  of  a  muscle,  in  every  action  of  the  brain,  some 
of  their  particles  are  worn  away. 

3.  The  body   is   always  active.     Even  in   sleep,  the 
breathing  muscles,  and  the  heart,  and  the  muscles  of  the 
digestive  organs,  are   moving.      The  wear  is,  therefore, 
constant. 

4.  But  the  body  differs  from  a  not-living  machine  in 
being  able  to  repair  itself.    In  early  life,  it  does  more  than 
this.     It  builds  itself  up,  and  grows.     When  it  has  got  its 
growth,  it  still   repairs  all  waste,  and   may  increase  in 
strength  and  endurance  for  many  years.     At  length  there 
comes  a  period  when  it  is  not  able  to  repair  so  much  as  it 
once  could ;  it  can  not,  therefore,  endure  so  much  wear, — 
the  old  can  not  be  so  active  as  the  young;  finally  it  is 
unable  even  to  supply  the  waste  caused  by  the  simplest 
actions,  such  as  breathing  and  digesting ;  then  life  must 
cease. 

SUGGESTION  TO  TEACHERS. — The  least  stain  of  blood,  on  a  glass  slide, 
under  a  microscope  magnifying  four  hundred  times,  is  sufficient  to  show 
the  red  globules.  It  is  not  always  easy  to  find  white  ones. 


WORK  AND    WASTE.  — THE  BLOOD.  f>l 

5.  Few  people  die  of  old  age.     Generally,  before  the 
time  for  such  a  death  is  reached,  some  disease  attacks  the 
enfeebled  body,  and  overcomes  it. 

6.  The  process  of  repair  is  going  on  all  the  time:  but, 
during  our  waking-hours,  waste  is  greater  than  repair; 
hence,  every  one. must  sleep  several  hours  in  each  twenty- 
four.     During  sleep,  the  waste  is  very  small;  and  the  pro- 
cess of  repair  restores  to  the  system  eax'h  night  what  it  has 
lost  during  the  day. 

7.  The  need  of  sleep  is  indicated  by  a  feeling  of  fatigue 
and  drowsiness.     These  are  the  warnings   that   Nature 
gives  us  to  stop  for  repairs.     Without  this   feeling,  we 
would  not  be  willing  to  lie  inactive  for  so  much  of  each 
day.     Since  rest  is  very  important,  this  feeling  is  made 
so  strong  that  it  is  almost  impossible  to  resist  it.      Ex- 
hausted men    will    fall    asleep    on    horseback,  or   even 
walking. 

8.  But  Nature  gives  her  warning  in  good  time.     If  it  is 
necessary  to  continue  working  for  a  while  after  we  begin 
to  feel  tired,  we  can  generally  do  so  without  injury;  but 
we  must  rest  afterward.     However  tired  we  may  be  at 
night,  if  we  are  rested  by  our  night's  sleep  we  are  safe ; 
but  if  the  wear  of  the  day  is  not  fully  repaired,  and  we 
feel  each  morning  more  weary  than  on  the  morning  be- 
fore, we  are  in  danger. 

9.  A  very  young  infant  sleeps  most  of  the  time.     He 
requires  less  sleep  as  he  grows  older.     Grown   persons 
need  from  six  to  nine  hours  sleep  every  day.     Indolent 
people  often  take  too   much.     On  the  other  hand,  it  is 
easy  to  injure  the  health,  particularly  in   early  life,  by 
taking  hours  which  belong  to  sleep  for  work  or  pleasure 
This  is   especially  injurious  when  the  weary  body  and 


THE  HUMAN   VODY. 


mind  are  excited  by  stimulants,  to  make  them  forget  the 
need  of  rest. 

10.  Sleep,  though  the  most  perfect,  is  not  the  only,  way 
of  resting.  When  we  have  been  using  the  muscles,  we 
may  rest  them  while  using  the  brain.  After  study,  hearty 
muscular  exercise  is  rest.  Entire  change  of  occupation  is 
rest. 

MATERIALS    FOR    REPAIR. 

SECTION  II. — 1,  The  materials  by  which  the  waste  of 
the  system  is  repaired,  are  found  in  air,  food,  and  water. 
Air  must  be  taken  in  constantly,  food  and  water  at  fre- 
quent intervals.  We  can  live  but  a  few  minutes  without 
air :  without  water  we  should  perish  in  a  few  days.  Men 
have  lived  without  food  for  weeks,  having  air  and  water; 
but  the  body  must  at  length  be  exhausted  if  these  three 
things  are  not  regularly  supplied  in  sufficient  quantity.  • 

2,  We  take  oxygen  from   the  air  by   the  breathing 
apparatus.     We  take  food  and  water  by  the  digestive 
apparatus.      Both  are  taken  into  the  blood,  and  carried 
through  the  body,  to  be  used  as  needed  in  every  part. 

3,  The  blood  not  only  carries  the  oxygen,  food,  and 
water  to  every  part  of  the  body:   it  also  carries  away 
from  every  part  the  ivaste  matter  which  is  formed  there, 
and  delivers  it  to  the  organs  which  discharge  it  from  the 
body.     It  has  been  likened  to  an  express-agent,  who  goes 
about  the  streets  of  a  city,  leaving  a  parcel  here,  taking 
one  there,  —  his  wagon  always  loaded,  though  its  contents 
are  constantly  changing. 

THE    BLOOD. 

SECTION  III. — 1.  Blood  is  a  red  fluid,  not  transparent, 
having  a  salty  taste.  It  is  a  little  heavier  and  thicker 


WOliK   ANT)    WASTE.  — THE   JiLOOD. 


53 


Fig.  27. 

RED  CORPUSCLES  OF  HUMAN 
BLOOD  (400  Diameters). 


than  water.     If  we  look  at  a  drop  of  it  through  a  micro- 
scope, we  shall  see  in  it  many  small  round  bodies,  shaped 
like  a  coin  with  a  thick  rim.     These 
are  only  MW   °f  an  mcn  across,  and 
are  all  of  the  same  size.     They  are 
called  red-blood  corpuscles,  or  glob- 
ules.    They  make  up  nearly  half  the 
blood. 

2,  Every  animal  that  has  a  back- 
bone has  red  globules  in  its  blood, 
but    they  differ  in   shape  and  size. 
In   birds  and   reptiles  they  are  not 

round,  but  oval,  in  shape,  and  have  a  spot  in  them  called 
a  nucleus.     In  all  animals  that  have  round  globules,  they 
are  smaller  in  size  than 
those  of  a  man's  blood, 
with  two  exceptions,  the 
elephant  and  the  sloth. 

3,  We  know  by  careful 
measurements  the  exact 
size  of  these  globules  in 
many   animals.     By  ex- 
amining a  drop  of  blood 
with  a  microscope,  we  can 
often  tell  what  animal  it 
came  from. 

4,  Such  examinations  are  made  of  blood  found  on  the 
clothing  of  persons  accused  of  murder,  and  aid  in  deter- 
mining  their  guilt  or  innocence.      But    this    evidence 
should  not  be  accepted  as  decisive.     There  are  possibili- 
ties of  mistake. 

5,  Besides  the  red  corpuscles,  there  are  also  white  cor- 


Fi£.  28. 

RED  CORPUSCLES  or  FROG'S  BLOOD  (400 
Diameters). 


54  77/7';   HUMAN    7iOJ)Y. 

puscles,  a  little  larger,  and  spherical  in  shape,  in  the  pro- 
portion of  one  white  one  to  three  or  four  hundred  red. 

6,  The  red  globules   have  the  property  of  attracting 
oxygen  to  themselves.     They  take  it  from  the  air  in  the 
lungs,  and  carry  it  to  all  parts  of  the  body. 

7,  These  globules  give  the  blood  its  red  color.     If  they 
were  all  taken  out,  it  would  be  transparent  and    color- 
less.    When  there  is  a  plenty  of  red  blood  in  the  blood- 
vessels, there  is  a  rosy  hue  in  the  cheeks,  and  the  lips  are 
cherry  red.     This  we  call  a  healthy  color.     It  is  healthy 
because  it  indicates  that  there  is  blood  enough,  and  that 
it  is  well  supplied  with  globules.     As  these  are  the  car- 
riers of  oxygen,  a  good  number  of  them  means  plenty 
of  oxygen  in  the  tissues;  and  that  is  necessary  to  good 
health.     On  the  other  hand,  colorless  lips  and  skin  indi- 
cate a  lack  of  red  globules,  scanty  oxygen,  and  ill  health. 

8,  The  watery  part  of  the  blood,  in  which  the  globules 
float,  is   called   the   plasma.      This   contains   many  sub- 
stances dissolved   in  it,  some  of  which  are  derived  from 
the  food,  and  nourish  the  body;  and  some  are  waste  mat- 
ters, which  the  blood  is  carrying  away  to  be  discharged. 

9,  When  blood  flows  out  of  the  blood-vessels,  it  soon 
thickens  into  a  jelly.     This  is  called  the  coagulation  of 
the  blood. 

10,  Blood  does  not  coagulate  in  the  blood-vessels  during 
life  if  they  are  sound.     If  the  blood  is  flowing  very  fast, 
it  will  not  coagulate  until  the  flow  is  checked.     If  the  air 
is  extremely  cold,  it  does  not  coagulate  quickly. 

11,  It  is  this  coagulation  of  the  blood  that  saves  us 
from  bleeding  to  death  when  we  are  wounded.     The  clots 
which  form,  stop  up  the  mouths  of  the  cut  vessels. 

12,  In  case  of  a  wound,  the  blood  should  be  helped  to 


WOUK  AND  WASTE.  — THE  BLOOD.        55 

coagulate,  by  pressing  on  the  spot  so  as  to  check  the  flow. 
Sometimes  it  is  necessary  to  tie  a  handkerchief  or  a  string 
around  the  limb  above,  or  sometimes  below,  the  wound. 
In  this  case  the  bandage  should  not  be  kept  on  too  long, 
as  other  parts  of  the  limb  may  suffer  from  want  of  blood. 

13,  Loss  of  blood  causes  great  weakness,  and  at  length 
fainting.    When  we  faint,  the  heart  almost  stops  its  action, 
and  the  flow  of  blood  becomes  very  slow.     This  gives  it 
an  opportunity  to   coagulate,  and   stop  up  the  bleeding 
vessels.     When  the  flow  of  blood  can  not  be  stopped,  a 
fainting-fit  may  save  life. 

14,  The  body  of  a  man  contains  six  or  eight  quarts  of 
blood.    The  loss  of  more  than  half  of  his  blood  would 
be  certainly  fatal,  and  the  loss  of  a  very  much  smaller 
portion  might  be  so. 

15,  People  near  to  death  from  loss  of  blood  have  some- 
times been  restored  by  throwing  into  their  veins  blood 
drawn  from  another  person.     This  is  called  transfusion. 
It  is  a  delicate  and  dangerous  operation,  and  not  often 
useful. 

16,  Some  causes  of  impure  blood  are, — 

1.  Bad  air. 

2.  Lack  of  exercise.    This  makes  the  flow  sluggish.    The 
organs  whose'  work   it   is   to  purify  it   become   inactive. 
Waste  matter  accumulates. 

s.  Too  much  or  too  rich  food.  The  blood  becomes  loaded 
with  matters  which  the  system  can  not  use  and  can  not 
easily  get  rid  of. 

4-  Too  little  or  too  poor  food.  The  blood  becomes  thin, 
and  unequal  to  the  nourishment  of  the  body. 

5.  Alcohol,  which  is  itself  an  impurity,  and  unfits  the 
blood  for  its  work. 


56  THE   HUMAN   BODY. 

17.  Bad  air  is  air  that  has  lost  its  oxygen  by  being 
breathed,  or  that  has  gases  in  it  that  do  not  belong  to 
fresh   air.     These   gases   commonly   smell   badly.     They 
come  from  decaying  or  other  foul  matters.     Good  air  has 
no  odor,  and  it  is  safe  to  follow  our  noses  when  they 
guide  us  out  of  any  close  place.     But  some  of  the  very 
worst  air  has   no  odor,  and  we   must  have  other  tests 
than  our  noses. 

18,  The  causes  of  impure  blood,  just  mentioned,  are 
apt  to  go  together,  and  help  each  other.     The  person  who 
eats  too  much  will  not  want  to  exercise,  while  he  needs 
the  more  to  do  so. 

Moderate  use  of  alcohol  often  excites  the  appetite  for 
rich  food  to  excess.  The  inordinate  drinker  is  apt  to  lose 
his  appetite,  and  take  too  little  food.  Often  he  can  digest 
but  little. 


QUESTIONS. 

SECTION  I.  —  1,  How  does  the  body  wear  out  ? 

4,  How  is  it  kept  in  repair  ?    Why  must  it  finally  die  ? 

6,  Why  do  we  need  sleep  ? 

7,  Why  is  sleepiness  a  safeguard? 

8,  How  can  we  know  that  we  are  not  wearing  out,  when  working 
very  hard  ? 

9,  How  much  sleep  does  a  grown  person  need  ? 
10,  Is  sleep  the  only  rest  ? 

SECTION  II.  —  1,  From  what  materials  is  the  waste  of  the  body 
repaired?    What  is  the  most  important? 

2,  How  do  we  take  in  oxygen?    How  do  we  take  in  food  and 
water  ?    How  are  these  distributed  through  the  body  ? 

3,  What  does  the  blood  carry,  besides  the  materials  for  repair? 

SECTION   III.  —  1,   What  is  blood?    What  are  blood-globules? 
What  is  their  size?    What  proportion  of  the  blood  do  they  make? 


WORK    AND     WASTE.  — THE    BLOOD.  59 

2,  What  animals  have  red  globules  in  their  blood  ?    What  is  their 
shape  in  man's  blood?    What  is  their  shape  in  bird's  blood?    What 
animals  have  larger  red  globules  in  their  blood  than  man  ? 

3,  4,  How  can  we  distinguish  the  blood  of  different  animals  ? 

5-7.  What  globules  are  there,  besides  the  red  ones?  How  nu- 
merous are  they  ?  What  do  the  red  globules  do  ?  What  makes  the 
blood  red  ?  Why  do  we  say  that  rosy  cheeks  are  a  sign  of  health  ? 

8.  What  is  the  plasma  of  the  blood  ?    What  does  it  contain  ? 

9-12,  What  is  the  coagulation  of  the  blood  ?  Does  blood  coagu- 
late in  the  blood-vessels  during  life  ?  What  hinders  coagulation  ? 
What  is  the  use  of  coagulation  ?  How  should  we  treat  a  bleeding 
wound  ? 

13.  How  may  a  fainting-fit  be  of  advantage  to  a  wounded  person  ? 

14, 15,  How  much  blood  is  there  in  the  body  ?  and  how  much 
may  be  lost  without  a  fatal  result  ?  What  is  transfusion  ? 

16-18,  Mention  causes  of  impure  blood.  What  is  bad  air  ?  How 
do  the  causes  of  impure  blood  help  each  other  ? 


EXPLANATION    OF    FIGURE. 

THE  figure  on  the  opposite  page  shows  the  heart  and  the  great  blood- 
vessels. The  arteries  are  colored  red,  the  veins  are  colored  blue. 

The  right  auricle  and  right  ventricle  of  the  heart  are  seen,  and  the 
beginning  of  the  pulmonary  artery,  coming  from  the  right  ventricle. 
Arching  from  the  heart,  and  passing  down  the  back,  is  the  aorta  (red). 
It  divides,  at  its  termination,  into  the  two  common  iliac  arteries.  The 
carotid  arteries  pass  up  on  the  sides  of  the  neck.  The  subclavian  arteries 
pass  off  to  the  right  and  left,  and  are  continued  as  the  axillary  arteries. 
The  venae  cava3,  ascending  and  descending,  lie  by  the  side  of  the  aorta. 
The  internal  jugular  vein  accompanies  the  carotid  arteries.  The  external 
jugular  is  just  outside  of  the  internal.  The  other  veins  have  the  same 
names  as  the  arteries  which  they  accompany.  The  intercostal  arteries 
and  veins  run  along  the  edges  of  the  ribs  on  each  side.  The  kidneys  are 
seen,  one  on  each  side  of  the  aorta. 


GO  THE  HUMAN   BODY. 


CHAPTER   V. 
THE     CIRCULATION. 

SECTION  I. — 1,  The  blood  is  found  in  every  part  of  the 
body.  But  the  body  does  not  hold  it  as  a  sponge  holds 
water.  It  is  rather  like  a  house  which  has  a  supply  of 
water  carried  through  it  in  pipes.  The  blood  in  the  body 
is  all  contained  in  pipes,  called  blood-vessels. 

2,  It  is  constantly  in  motion.     Starting  from  the  heart, 
it  moves  through  the  blood-vessels  off  to  distant  parts  of 
the  body,  and  then  back  to  the  heart  again,  making  a 
circle.     The  heart  and  blood-vessels  are,  therefore,  called 
the  organs  of  circulation. 

3,  The  blood-vessels  are  called  arteries,  capillaries,  and 
veins.     Coming  out  of  the  heart  is  a  very  large  artery, 
called  the  aorta.     This  gives  off  branches  as  it  passes  on, 
and  these  branches,  again,  other  branches,  growing  smaller 
as  they  divide,  until  at  length  the  smallest  branches  are 
called  capillaries. 

4,  The  capillaries  are  very  numerous,  very  small,  and 
very  close  together.     They  form  a  net-work  in  every  inch 
of  bone  and  muscle  and   skin  and  brain,  —  a  net-work 
finer  than  the  finest  silk.     We  can  not  put  a  fine  needle- 
point into  the  skin  without  opening  some  of  these  capil- 

SUGOESTIONS  TO  TEACHERS.  —  SECTION  I.  A  beefs  or  sheep's  heart,  from 
the  butcher's,  will  show  all  the  parts  named  in  the  text.  The  action  of  the 
heart-muscle  and  of  its  valves  may  be  partly  illustrated  with  a  Davidson's 
syringe. 


THE   CIRCULATION.  Gl 

laries,  and  drawing  blood,  so  close  together  they  are.  If 
we  could  take  out  from  the  body  of  a  man  all  the  flesh 
and  bone,  leaving  the  blood-vessels,  there  would  still  be 
sufficient  to  form  a  perfect  figure. 

5,  The  arteries  divide  up  into  the  capillaries,  and  the 
capillaries  unite  to  form  the  veins.     The  little  veins  thus 
formed,  unite  to  form  larger  veins,  and  so  on,  until  at  last 
they  are  all  gathered  into  two  large  veins  which  enter  the 
heart.     These  are  called  the  vena  cava  superior,  and  the 
vena  cava  inferior. 

6,  The  walls  of  the  capillaries  are  very  thin.    Although 
there  are  no  openings  in  them,  a  portion  of  the  blood 
soaks  through  into  the  surrounding  tissues;  and,  on  the 
other  hand,  fluids  containing  waste  matter  soak  into  them, 
to  be  carried  away. 

THE   HEART. 

SECTION  II.  —  1,    The  heart  is  made  of  muscle,  and  is 
hollow.     It  is  the  pump  which  keeps  the  blood  moving. 

2,  It  is  situated  in  the  chest,  resting  on  the  diaphragm, 
chiefly  on  the  left  side  of  the  middle  line.     It  is  shaped 
like  a  pear,  with  the  small  end  pointing  down,  and  to  the 
left. 

3,  It  is  inclosed  in  a  sac  called  the  pericardium.     This 
sac  is  also  pear-shaped;  but  the  large  end  is  on  the  dia- 
phragm, and  the  small  end  points  up. 

4,  The  pericardium  is  lined  with  a  very  smooth  mem- 
brane.    The  heart  is  covered  with  a  continuation  of  the 
same   membrane.     This   membrane   is   kept   glossy  and 
moist  by  a  fluid  that  it  gives  out.    When  the  heart  moves 
in  its  sac,  these  two  smooth  membranes  rub  together  with- 
out friction. 


02 


THE  HUMAN  BODY. 


5,  The  apex,  or  point,  of  the  heart  is  just  beneath  the 
fifth  rib.      Its  base  is  a  little  to  the  right  of  the  breast- 
bone.    It  extends  up  as  high  as  the  third  rib.     It  is  held 
in  place  by  the  diaphragm  beneath  it,  and  the  large  blood- 
vessels which  run  into  and  out  of  it.     It  is  about  as  large 
as  the  fist,  weighing  from  eight  to  twelve  ounces. 

6,  We  find,  on  examining  the  interior,  that  it  is  divided 
into  four  cavities.     There  is  a  division  which  runs  across, 


Pulmonary  artery. 


Aorta. 


Vena  cava  superior. 


Pulmonary  veins.  •*"...... 

Right  auricle.  - • 

Tiicuapid  valve /; 

Vena  cava  inferior - 


Right  ventricle.    •••' 


Pulmonary  artery. 


—-.•Pulmonary  veins. 


••—  Left  auricle. 
Mitral  valve. 


Left  ventricle. 


Aorta. 


Fig.  29. 
REPRESENTATION  OF  A  SECTION  or  THE  HEART  (Diagrammatic). 

and  one  which  runs  lengthwise.  This  last  divides  it  into 
right  and  left  sides,  the  other  into  auricles  (Latin,  auricula, 
the  external  ear)  and  ventricles  (Latin,  ventricnlus,  the 
belly).  These  cavities  are  of  nearly  the  same  size,  each 
holding  about  three  ounces.  The  walls  of  the  auricles 
are  thin  and  loose.  The  wall  of  the  right  ventricle  is 
about  a  sixth  of  an  inch  thick.  That  of  the  left  ventricle 
is  half  an  inch  thick. 

7,    The  two  large  veins  which  bring  the  blood  from  the 


THE  CIRCULATION. 


body  back  to  the  heart,  open  into  the  right  auricle.  Be- 
tween the  right  auricle  and  the  right  ventricle,  there  is 
an  opening  about  an  inch  in  diameter.  This  opening  is 
closed  by  the  tricuspid  (three-pointed)  valve.  This  con- 
sists of  three  thin  flaps,  whose  edges  meet  when  the  valve 
is  shut.  This  valve  opens  from  the  auricle,  and  shuts  so  as 
to  prevent  the  blood  from  passing  back  from  the  ventricle 
to  the  auricle.  There  are  fine  cords  attached  to  the  edges 
of  these  flaps,  and  to  the  wall  of  the  cavity  below,  to  pre- 
vent their  shutting  back  too  far. 

8.  Opening  out  of  the  right  ventricle  is  the  pulmonary 
artery.     This  soon  divides  into  two,  one  of  which  goes  to 
the  right,  the  other  to  the  left,  lung.     They  there  divide 
into  capillaries,  and 

the  capillaries  pass 
into  the  pulmonary 
veins.  These  are 
two  in  number  for 
each  lung.  They 
empty  into  the  left; 
auricle. 

9.  At  the  begin- 
ning of  the  pulmo- 
nary artery  is  a  set  of  valves  which  prevent   the  blood 
from  flowing  back  into  the  heart.     These  valves,  called 
semilunar  valves,  are  three  pockets  hung  on  the  wall  of 
the  artery,  their  edges  meeting  all  around.      They  open 
away  from  the  heart;  and,  when  the  blood  is  going  in 
that  direction,  they  flatten  up  against  the  wall,  just  as  a 
pair  of  doors  will  when  a  crowd  is  pushing  through  them. 
When  the  blood  sets  back  toward  the  heart,  it  fills  the 
pockets;  and  they  bulge  out,  and  together  fill  the  tube, 


Fig.  30. 
BBMILUNAR  VALVES  OPEN. 


64 


THE  HUMAN    VODY. 


Fig.  31. 

SEMILUNAR  VALVES 
PARTLY  CLOSED. 


and  stop  it  up.     These  are  very  perfect  valves.     They  are 
flexible,  and  float  open  like  thin  veils  when  the  blood 
wishes  to  pass  in  the  right  direction;  but  they  are  strong; 
and,  the  harder  it  presses  back,  the  tighter  they  fit. 
10,    The  left  auricle  is  similar  to  the  right.    The  opening 
between  it  and  the  left  ventricle  is  an 
inch  in  diameter,  and  is  closed  by  the 
mitral  valve. 

The  mitral  valve  differs  from  the  tri- 
cuspid  in  having  two  flaps  instead  of 
three.  When  closed,  it  resembles  a 
miter,  or  bishop's  cap. 

11,  The  left  ventricle  differs  from  the 
right  only  in  having  thicker  walls. 

12,  Out  of  the  left  ventricle  opens 
the  great  artery  of  the  body,  the  aorta. 

Its  entrance  is  guarded  by  semilunar  valves  precisely  like 
those  of  the  pulmonary  artery  described  above.  It  gives 
off  numerous  branches,  which  go  to  all  parts  of  the  body, 
finally  dividing  into  capillaries.  From  these  capillaries 
the  blood  is  returned  by  the  veins  to  the  right  auricle. 

13,  The  muscle  of  which  the  heart  is  composed  is  pe- 
culiar. It  is  striped,  and  yet  not  voluntary.  As  it  must 
act  during  sleep,  it  is  made  independent  of  will  or  thought. 

The  heart  and  the  blood-vessels  are  lined  by  a  mem- 
brane as  smooth  as  satin. 

jf 

ACTION   OF   THE  HEART. 

SECTION  III. — 1,  The  heart  is,  in  the  body,  what  the 
mainspring  is,  in  a  watch.  *Like  all  other  muscle,  it  has 
the  power  of  contracting.  By  constant  and  regular  con- 
tractions it  keeps  up  the  circulation,  and  thus  sustains  life. 


TUP:  CIRCULATION.  65 

2,  The  heart-muscle  is  remarkable  for  its  endurance. 
No  other  muscie   could  do  its  work.     Through  a  whole 
lifetime,  sometimes  a  hundred  years,  it  never  pauses  for 
one  minute. 

3,  It  might  seem,  therefore,  to  be  an  exception  to  the 
general  law,  that  rest  is  necessary  for  all  organs;  but,  after 
each  contraction,  it  has  a  very  short  time  of  relaxation  and 
rest.     This  time  is  not  more  than  two-fifths  of  a  second; 
but,  as  it  comes  every  second,  its  whole  amount  in  twenty- 
four  hours  would  be  eight  or  nine  hours.     Moreover,  in 
sleep  the  heart  beats  less  rapidly,  and  is  not  obliged  to 
make  the  special  efforts  which  are  so  often  required  of  it 
during  the  day  by  rapid  movements  or  excitement. 

4,  The  heart  is,  doubtless,  tired  after  labor,  and  con- 
tributes to  the  general  sense  of  fatigue;  but  in  health  we 
have  no  special  feeling  of  the  heart.     Great  and  long-con- 
tinued care  such  as  business  men  are  often  subjected  to, 
or  protracted  muscular  exertion  like  that  of  soldiers  on  a 
march,  sometimes  so  exhausts  the  heart,  that  it  acts  irreg- 
ularly,  and    feels    distress.      This    condition,  known    to 
physicians  as  "  irritable  heart,"  maybe   brought  on  by 
prolonged  dissipation. 

5,  The  number  of  heart-beats  in  a  minute  varies  at  dif- 
ferent periods  of  life.     In  an  infant  it  is  one  hundred  and 
twenty  or  more;   in   a   child   under   fourteen,  eighty  or 
more;  in  a  grown  person,  about  seventy -two.     But  it  may 
be  ten  beats  more  or  less;  and,  in  rare  cases,  there  is  a  still 
wider  variation  in  health. 

6,  Many  things  cause  a  temporary  variation.     It  is  less 
in  sleep:  it  is  greater  in  active  exercise.     One  reason  why 
we  soon  become  exhausted  by  running,  is  that  the  heart 
is  stimulated  to  such  japid  action.     It  is  greater  after  eat- 


THE  HUMAN   BODY. 


ing  in  moderation.  Excitement  of  any  kind  increases  the 
number  and  force  of  heart-beats  so  that  they  can  be  felt, 
and  sometimes  heard.  In  the  affection  called  palpitation, 
the  action  of  the  heart  is  unnaturally  rapid,  and  some- 
times hard  enough  to  shake  the  body. 

7,    The  heart  has  been  called  a   pump.      It  is  really 
a  double  pump.     There  are  two  streams  flowing  out  of 
it  with  each  contraction,  and  two  streams  flowing  into  it 
with  each  relaxation.     The   two  sides 
of  the  heart  have  no  direct  communi- 
cation, and  are  often  spoken  of  as  the 
right  and  left  heart,  as  if  they  were 
separate. 

8.  There  are,  accordingly,  two  dis- 
tinct circles  of  blood.  One  begins  at 
the  right  ventricle,  goes  through  the 
pulmonary  artery  to  the  lungs,  and 
back  through  the  pulmonary  veins  to 
the  left  auricle.  This  is  called  the 
pulmonary  circulation,  or  the  lesser 
circulation. 

Fi    32  The  other  begins  at  the  left  ventricle, 

REPRESENTATION  OF  THE  and  goes  through  the  aorta,  to  be  clis- 
GREATER  AND  LESSER  tributed  to  all  parts  of  the  body,  and, 

CIRCULATION.  \ 

passing  through  the  capillaries  and 
veins,  is  poured  into  the  right  auricle  by  the  vena  cava 
superior  and  the  vena  cava  inferior.  This  is  called  the 
systemic  or  greater  circulation. 

9,  Let  us  observe  a  contraction  and  its  effect.  Suppose 
the  auricles  to  be  full.  The  blood  has  been  pouring 
into  the  right  one  from  the  venae  cavoe,  and  into  the  left 
from  the  pulmonary  veins.  Now  the  auricles  contract. 


Til  K   CI II C  UL  A  TWN. 


Their  contents  can  not  go  back  into  the  veins,  for  they 
are  full;  but  the  ventricles  have  just  emptied  them- 
selves, and  are  opening  for  a  new  supply.  The  blood  is 
therefore  forced  suddenly  on  through  the  passages,  with 
their  open  valves,  into  the  ventricles.  Directly  the  ven- 
tricles, now  full,  begin  to  contract.  The  blood  sets  back 
against  the  valves  it  has  passed,  and  shuts  them  tight, 
just  as  a  crowd  trying  to  get  through  a  door  which 
opens  towards  them  will  often  close  it:  but  the  passages 
into  the  pulmonary  artery  and  the  aorta  are  clear, — 
their  valves  (the  semilunar}  open  out;  into  them  the 
blood  pours,  the  ventricles  still  contracting  until  all  is 
squeezed  out.  Then  the  blood  in  the  arteries  sets  back, 
and  shuts  the  semilunar  valves;  and  the  ventricles  re- 
lax, and  open  for  another  supply. 

SOUNDS   OP  THE  HEART. 

SECTION  IV. — 1,  If  the  ear  be  placed  upon  the  chest 
over  the  heart,  two  sounds  can  be  distinctly  heard,  re- 
peated with  each  beat.  '  One  is  quickly  followed  by  the 
other,  and  then  there  is  an  interval.  The  second  is 
shorter,  and  higher  pitched  than  the  first.  They  may  be 


indicated  by  the  signs  —4       +~    The  first  sound  is 

lub  -  dub. 

caused  chiefly  by  the  closing  of  the  tricuspid  and  mitral 
valves,  as  the  ventricles  contract.  The  second  sound  is 
caused  by  the  closing  of  the  semilunar  valves  after  the 
blood  has  passed  into  the  pulmonary  artery  and  aorta. 
When  the  heart  is  diseased,  these  sounds  are  changed  ; 
and  the  changes  in  sound  indicate  to  the  ear  of  the 
physician  the  particular  changes  in  the  heart. 


68 


77/7?   HUMAN  J10DY 


_»Subclavian. 


Femoral 


Anterior  tihial.  - 


I>orsal  of 
the  foot. 


Fig.  33. 
REPRESENTATION  OP  THE  ARTERIES. 


THE   ARTERIES,   VEINS,    AND    CAPILLARIES. 

SECTION   V.  —  1,    The   aorta   arches  from  the  base   of 
the  heart  across  to  the  backbone;  by  the  side  of  which 


THE  CIRCULATION.  G9 

it  descends.  On  a  level  with  the  top  of  the  hip-bones,  it 
divides  into  two  vessels,  one  of  which  supplies  each  of  the 
lower  limbs.  From  the  arch,  branches  are  given  off, 
which  supply  the  head  and  the  arms. 

2,    In  the  thigh,  the  large  vessel  which  carries  the  main 
stream  is  called  the  femoral  artery.     In  the  leg  it  is  called 
the  tibial  artery. 
S  3,    The  carotid  arteries  carry  the  blood  from  the  arch  to 

/  the  head.  They  pass  up  on  each  side  of  the  neck,  and 
their  throbbing  can  often  be  seen.^  The  subclavian  ar- 
teries lie  behind  the  collar-bones.  They  extend  to  the 
armpit,  and  in  that  situation  receive  the  name  axillary. 
From  the  armpit  to  the  elbow  they  are  called  brachial. 
At  the  elbow  they  divide  into  the  radial  and  ulnar.  The 

V  radial  lies  on  the  thumb-side  of  the  fore-arm,  and  is  the 

\one  in  which  the  pulse  is  commonly  felt. 

4,  All  the  large  arteries  lie  deep.     They  can  be  felt  or 
seen  on  the  surface,  only  in  a  few  places.     But  many  large 
veins  lie  just  beneath  the  skin,  and  can  be  traced  for  some 
distance. 

The  deep  veins  run  by  the  side  of  the  arteries. 

5,  The  veins  frequently  have  the  same  names  as  the 
arteries  which  they  accompany.      Sometimes  they  have 
special  names.     The  large  veins  of  the  neck  are  called 
jugular  veins.     The  superficial  jugular  is  the  prominent 
vein  just  beneath  the  skin  on  each  side. 

6,  The  blood  flows  in  the  large  arteries  much  more 
rapidly  than  in  the  small  ones.     Its  flow  is  slower  in  the 
veins  than  in  the  arteries.      It  is  slowest  of  all  in  the 
capillaries.     This   is   for   the   same   reason   for  which   a 
stream  flows  more  slowly  when  its  channel  is  wide  than 
when  it  is  narrow.     The  capillaries  are  very  small;  but 


THE   HUMAN   BODY. 


Fig.  34. 
CAPILLARY  PLEXUS  MAGNIFIED. 


there  are  so  many  of  them,  that  their  total  blood-channel 
is  really  wider.  It  is  estimated  that  it  is  three  hundred 
times  as  wide  as  the  aorta. 

7.  Though  many  men  of  great  minds  gave  much  study 
to  the  human  body,  it  was  not  learned  until  less  than 
three  hundred  years  ago  that  the  blood  circulated.  Wil- 
liam Harvey,  an  English  physician,  made  the  discovery, 

and  gave  it  to  the  world. 

8,  The  walls  of  the  capillaries 
are  a  single  layer  of  a  thin  mem- 
brane.   Through  them  nutritious 
fluids  soak  out,  and  waste  fluids 
soak  in. 

9,  Some  points  in  which  ar- 
teries and  veins  differ :  — 

1.  In  the  direction  of  their  cur- 
rent. In  arteries  it  always  runs  from  the  heart :  in  veins 
it  always  runs  toward  the  heart. 

2.  In  position.  We  do  not  find 
large  arteries  running  just  beneath 
the  skin,  as  veins  do. 

s.  In  color.  The  blue  tint  of  their 
blood  shows  through  the  walls  of 
the  veins. 

4.  In  thickness.     The  arterial  walls 
are  thicker  and  firmer. 

5.  The  veins  have  valves  at  inter- 
vals in  their  course,  which  allow  the 
blood   to    move    forward,   but  not 
backward. 

10,  In  case  of  a  wound,  we  can 
tell  whether  the  blood  is  from  an  artery  or  a  vein  — 


Fig.  35. 

VEIN  LAID  OVEN,  SHOWING 
THE  VALVES. 


THE   CIRCULATION.  71 

1.  By  its  color.    Venous  blood  is  dark :  arterial  blood  is 
light. 

2.  By  the  manner  of  its  flow.    Venous  blood  flows  in  a 
steady  stream,  arterial  blood  in  jets. 

11,  The  flow  of  blood  from  a  vein  stops  more  readily 
than  that  from  an  artery.     A  bandage  is  commonly  suf- 
ficient.    The  arterial  flow  is  more  forcible.     When  the 
blood  spurts,  it  must  be  checked  by  firm  pressure  on  the 
vessel  until  a  physician  arrives.     It  may  be  necessary  to 
tie  the  artery. 

The  pulmonary  artery  is  peculiar  because  it  carries 
blue  venous  blood.  The  pulmonary  veins  carry  red  ar- 
terial blood.  In  these  respects  they  are  exceptions  to  the 
general  rule. 

12.  Arteries  and  veins  are  very  strong.     In  experiments 
made,  they  have  borne  a  pressure  equal  to  a  weight  of  a 
hundred  pounds  without  bursting.     But  they  sometimes 
burst.     In  old  age  they  become  brittle.     Certain  diseases 
make  them  brittle. 

THE  PULSE. 

SECTION  VI.  —  1.  At  a  certain  spot  in  the  wrist,  we  can 
feel  a  regular  beat,  which  we  call  the  pulse.  A  pulse  may 
be  felt  in  several  other  places,  but  the  wrist  is  the  most 
convenient.  The  pulse  is  a  sudden  rising-up  of  the  wall 
of  the  artery  under  the  finger,  and  a  slight  stirring  of  the 
whole  artery  in  its  bed. 

2.  Every  time  the  heart  contracts,  about  six  ounces  of 
blood  are  thrown  into  the  arteries.  These,  being  elastic, 
stretch  to  receive  it.  Between  the  beats  they  contract, 
forcing  the  blood  along  into  the  capillaries. 

This  stretching  is  greatest  in  the  aorta,  close  by  the 


72  THE   HUMAN   HODY. 

heart,  and  diminishes  as  the  vessels  grow  smaller.     By 
the  time  the  capillaries  are  reached,  there  is  no  stretching, 
hence  no  pulse.     The  veins  have  no  pulse. 
3.    The  pulse  tells  us, — 

1.  How  fast  the  heart  is  beating. 

2.  How  strong  its  beat  is. 

5.  How  firm  the  coats  of  the  arteries  are.  The  last  fact 
is  important.  The  arterial  walls  are  sometimes  flabby, 
and  sometimes  hard  and  resisting.  Their  condition  indi- 
cates the  state  of  the  system. 

VARIATIONS   IN    BLOOD-SUPPLY. 

SECTION  VII. — 1,  You  might  suppose,  from  what  has 
been  said  of  the  circulatory  apparatus,  that  the  same 
blood-vessels  are  always  of  the  same  size,  and  that  the 
blood-supply  to  the  same  part  is  at  all  times  of  the  same 
amount.  This  is  not  the  case.  Although  there  are  no 
stopcocks  in  the  blood-vessels,  there  is  a  contrivance  of 
Nature  by  which  the  size  of  the  blood-vessels  and  the 
amount  of  blood  in  any  part  is  increased  or  diminished 
according  to  the  need  of  the  moment. 

2.  In   this  way  the  blood  is  partly  shut   off  from   the 
brain  when  we  need  sleep;  it  is  turned  on  to  the  stomach 
during  digestion,  and  to  the  muscles  in  active  exercise;  it 
is  shut  off  from  the  skin  when  it  is  cold,  and  sent  there 
to  be  cooled  when  we  are  warm. 

3,  The  walls  of  the  arteries  consist  partly  of  fibers  of 
involuntary  muscle  running  crosswise.     AVhen  these  mus- 
cle-fibers contract,  they  make  the  artery  smaller:    when 
they  are  relaxed,  it  is  larger.     They  are  not  under  the 
control  of  the  will,  but  are  influenced  by  special  causes. 
For  example,  the  arteries  in  the  coats  of  the  stomach  will 


THE  CIRCULATION. 


grow  larger  when  food  touches  it.  The  arteries  of  the 
salivary  glands  will  grow  larger,  and  fill  with  blood  for 
the  manufacture  of  saliva,  when  we  smell  food,  thus  "mak- 
ing the  mouth  water."  The  arteries  of  the  skin  will  grow 
larger,  and  fill  with  red  blood,  when  exposed  to  heat.  The 
arteries  of  the  face  will  expand,  and  cause  a  blush,  when 
we  feel  shame. 

4,  The  apparatus  which  regulates  the  size  of  the  arte- 
ries belongs  to  the  nervous  system. 

EFFECT   OF   ALCOHOL   ON   THE   CIRCULATION. 

SECTION  VIII.  —  1,  The  heart  of  a  grown  person  beats 
about  seventy-two  times  in  a  minute.  The  total  number 
of  strokes  in  a  day  is  over  a  hundred  thousand.  In  mak- 
ing this  number  of  strokes,  it  exerts  force  enough  to  lift 
over  a  hundred  tons  weight  one  foot  from  the  ground. 
Alcohol  makes  the  heart  of  a  well  person  beat  faster. 
Very  careful  experiments  made  by  Drs.  Parkes  and  Wol- 
lowicz  show  that  the  drinking  of  a  moderate  amount  of 
alcohol — not  more  than  two  ounces  in  a  day — will  add 
to  the  force  exerted  by  the  heart  four  per  cent,  enough  to 
lift  four  tons  weight  one  foot. 

This  extra  effort  of  the  heart  is  unnecessary ;  it  is  of  no 
use  to  the  body;  and,  since  it  is  made  under  an  unnat- 
ural stimulus,  it  is  exhausting. 

2.  The  smaller  blood-vessels  are  dilated  by  the  influ- 
ence of  alcohol.  The  face  is  flushed ;  and  the  internal 
organs,  if  we  could  see  them,  would  look  redder.  At  first, 
the  flushing  passes  off  after  a  certain  time,  and  the  blood- 
vessels return  to  their  natural  size.  But,  after  long  use  of 
spirits,  they  remain  dilated.  The  red  nose  is  an  index 
of  the  state  of  many  parts  of  the  body.  This  is  an  unnat- 
ural and  unhealthy  condition. 


74  THE    HUMAN    BODY. 

3.  Alcohol  has  the  power  to  change  muscle  gradually 
into  fat.     The  heart  is  particularly  liable  to  this  change. 
As  the  fibers  soften  down,  it  loses  its  strength.     It  can 
not  do  the  work  of  pumping  the  blood  through  the  body 
with  its  natural  vigor.     The   body,  therefore,  suffers   in 
every  part.     Such  a  fatty,  soft  heart  is  liable  to  break 
suddenly. 

4.  As  old  age  comes  on,  the  walls  of  the  arteries  fre- 
quently become  changed  in  previously  healthy  persons. 
They  get  fatty  and  soft,  or  chalky  and  brittle,  in  spots. 
In  this  state  they  easily  burst,  if  by  excitement,  or  over- 
eating, or  some  other  cause,  they  are  unusually  full.     This 
is  especially  liable  to  occur  in  the  blood-vessels  of  the 
head.     The  blood  pours  out;  and,  as  the  skull  is  a  tight 
box,  the  brain  is  pressed  so  hard  that  it  can  not  act. 
The  person  so  affected  becomes 'unconscious,  and  is  very 
likely  to  die.     This  takes  place  suddenly,  and  it  is  called 
apoplexy. 

5.  Apoplexy    is    a    disease    of    advanced    life.     These 
changes  do  not  take  place  in  the  arteries  of  the  young 
without   special   causes.     Alcohol   is    such    a    cause.     It 
makes  the  young  man  old  before  his  time,  and  liable  to 
sudden  death  by  the  rupture  of  an  artery  in  the  brain. 


QUESTIONS. 

SECTION  I.  —  1.  In  what  way  is  the  blood  held  in  the  body  ? 

2,  Why  are  the  heart  and  blood-vessels  called  organs  of  circula- 
tion? 

3,  What  are  the  three  kinds  of  blood-vessels  ? 

4,  Describe  the  capillaries. 

SECTION  II.— 1,  What  is  the  heart? 


THE    CIRCULATION.  75 

2,  Where  is  it  situated  ? 

3,  What  is  the  pericardium  ? 

4,  How  is  friction  from  the  movements  of  the  heart  avoided  ? 

5,  Where  is  the  apex  of  the  heart  ?    How  high  does  it  extend  ? 
How  is  it  held  in  place  ?    How  large  is  it  ? 

6,  How  is  its  interior  divided  ?     Name  its  cavities.     What  is  the 
size  of  each  ?    What  is  the  thickness  of  their  walls  ? 

7,  Describe  the  passage  between  the  right  auricle  and  ventricle, 
and  its  valve.    What  vessels  open  into  the  right  auricle  ? 

8,  What  vessel  opens  out  of  the  right  ventricle  ?    What  is  its 
course  ?    What  vessels  empty  into  the  left  auricle  ? 

9,  Describe  the  semilunar  valves  of  the  pulmonary  artery. 

10,  Describe  the  passage  between  the  left  auricle  and  ventricle, 
and  its  valve. 

11,  What  is  the  difference  between    the    left    and    the    right 
ventricle  ? 

12,  Describe  the  aorta  and  its  valves. 

13,  Describe  the  muscle  of  the  heart. 

SECTION  III.  —  1.  What  does  the  heart  do  ? 

2,  Does  the  heart  get  tired  ? 

3,  How  does  the  heart  rest  ? 

4,  How  many  times  does  the  heart  beat  in  a  minute  ? 

5,  What  causes  make  the  number  of  beats  in  a  minute  greater 
or  less  ?  ^ 

6,  Why  may  the  heart  be  called  a  double  pump  ? 

7,  What  is  the  lesser  circulation  V    What  is  the  greater  circula- 
tion? 

8,  Describe  in  full  a  contraction  of  the  heart. 

SECTION  IV.  —  1.  What  sounds  does  the  heart  make,  and  how  ? 

SECTION  V.  —  1.  Describe  the  course  and   termination    of  the 
aorta. 

2,  Where  is  the  femoral  artery  ?  the  tibial  ? 

3,  Where  are  the  carotids,  the  subclavian  arteries,  the  axillary, 
the  brachial,  the  radial,  the  ulnar  ? 

4,  Do  large  arteries  run  as  near  the  surface  as  large  veins  ? 

5,  How  are  the  veins  named  ?    Where  are  the  jugular  veins  ? 


76  THE  HUMAN   BODY. 

6,  Where  does  the  blood  flow  fastest  ?    Where  slowest  ? 

7,  Who  discovered  and  proved  the  circulation  of  the  blood  ? 

8,  What  are  the  walls  of  the  capillaries  ? 

9,  Name  some  points  in  which  arteries  and  veins  differ. 

10,  How  can  we  tell,  in  case  of  a  wound,  whether  the  blood  comes 
from  an  artery,  or  from  a  vein  ? 

11,  Is  the  flow  from  a  vein  as  easily  stopped  as  that  from  an 
artery  ? 

12,  Are  veins  and  arteries  strong  ? 

SECTION  VI.  —  1.  What  is  the  pulse  ? 

2,  Is  there  any  pulse  in  the  capillaries  ?  in  the  veins  ?    How  does 
the  blood  flow  from  an  artery  ?    How  from  a  vein  ?    How  from  the 
capillaries  ? 

3,  What  does  the  pulse  tell  us  ? 

SECTION  VII.  —  1.  Is  the  supply  of  blood  to  the  same  part  always 
the  same  ? 

2-4,  How  is  it  made  greater  or  less  ? 

SECTION  VIII.  —  1-  What  is  the  immediate  effect  of  alcohol  on 
the  heart  ? 

2,  How  are  the  smaller  blood-vessels  affected  by  alcohol  ? 

3,  What  change  does  alcohol  sometimes  cause  in  the  substance 
of  the  heart  ? 

4,  What  change  does  alcohol  sometimes  cause  in  the  blood- 
vessels ?    What  is  apoplexy  ? 

5,  How  does  alcohol  cause  it  ? 


FOOD  AND    WATER,    STIMULANTS,   ETC. 


77 


CHAPTER  VI. 

FOOD    AND    WATER,     STIMULANTS    AND 
NARCOTICS. 

SECTION   I.  —  1,    By  food  we  mean  all  substances  that 
we  eat  or  drink  to  satisfy  hunger  and  nourish  the  hody. 

2.  If  we  have  to  repair  any  manufactured  article,  we 
use  the  same  kinds  of  material  that  the  article  was  made 
of.     We  repair  a  harness  with  leather,  a  stove  with  iron, 
a  table  with  wood.     So  our  food,  which  repairs  the  body, 
must  contain  the  same  substances  that  the  body  contains. 

3,  Analysis  by  the  chemist  shows  that  the  body  of  man 
consists  of  fifteen  substances,  called  elements. 1 


Elements.  Parts  in  100. 

Oxygen 72. 

Hydrogen 9.1 

Nitrogen 2.5 

Chlorine 085 

Fluorine 08 

Carbon 13.5 

Phosphorus 1.15 

Calcium  .  1.3 


Elements.  Parts  in  100. 

Sulphur 1476 

Sodium 1 

Potassium 026 

Iron 01 

Magnesium 0012 

Silicon 0002 

Manganese A  trace. 


4,    Our  food  must  contain  every  one  of  the  above  ele- 
ments.    Of  some,  the  body  contains  little ;  and  we  require 


1  These  substances  are  not  always  in  exactly  the  proportions  given  in 
the  table.  Each  would  differ  in  amount  in  different  bodies,  and  in  the 
same  body  at  different  times. 


78  THE  HUMAN  BODY. 

but  little  in  our  food.  Sulphur  is  one  of  these.  Others 
are  abundant  in  the  body,  and  are  found  in  almost  every 
article  of  food.  Carbon  is  one  of  these.  If  any  of  these 
elements  is  entirely  wanting  in  our  food,  we  suffer,  and 
would  starve  to  death  for  lack  of  some  of  them.  If  we 
should  try  to  live  on  food  which  contained  no  phosphorus, 
for  example,  we  should  become  diseased,  and  die.  Almost 
every  thing  that  we  eat  contains  phosphorus. 

5,  Other  elements  than  the  fifteen  given  above,  are  not 
required  in  our  food.     Silver,  for  example,  does  not  form 
part  of  the  body,  or  of  our  food ,  but  nitrate  of  silver  is 
sometimes  used  as  a  medicine. 

6,  All  of  these  fifteen  elements  are  found  in  the  air,  the 
earth,  and  the  water.     But  animals  can  not  feed  on  earth 
and  air  and  water.     Plants  can,  and  that  is  one  of  the 
great  distinctions  between  plants  and  animals       Four- 
fifths  of  the  air  is  nitrogen.     But  men,  and  other  animals, 
would  die  for  want  of  nitrogen,  even  while  they  were 
drawing  it  into  their  lungs  with  every  breath,  if  they 
could  not  get  food  containing  it. 

7,  It  is  the  ivork  of  plants  to  take  the  elements,  and  make 
them  into  food  for  animals.     The  plant  feeds  on  earth, 
air,  and  water.     This  earth,  air,  and  water  become  a  part 
of  itself.     The   animal  feeds   on  the  plant,  or  on  other 
animals. 

8,  Probably  every  plant  is  food  for  some  animal.     But 
there  are  very  many  which  are  not  food  for  man.     Some 
are  poisonous.     A  large  number   contain   the   necessary 
elements,  but  can  not  be  digested  by  the  human  organs  of 
digestion.     A  fertile  prairie  which  would  fatten  a  herd  of 
buffaloes  would  starve  a  man;  because  the  grasses,  though 
not  poisonous  or  distasteful,  contain  too  much  indigest- 
ible matter  for  his  stomach. 


FOOD  AND    WATER,    STIMULANTS,   ETC.  79 

9,  Some  animals  live  only  on  other  animals.      Their 
teeth    are    not    fit   for   chewing   vegetable  food.      Other 
animals  live  wholly  on  plants.     Their  teeth  are  made  for 
grinding,  hut  not  for  tearing  flesh.     The  cow,  for  example, 
has  no  cutting-teeth  in  her  upper  jaw.     She  has  broad 
grinders.      Man   eats  both   animal  and   vegetable  food. 
His  teeth  are  adapted  to  both. 

10,  The  infant,  and  the  young  of  many  of  the  lower 
animals,  live  on  milk.     No  other  article  of  food  so  well 
combines  all  the  necessary  elements  as  this.     It  is  easily 
digested,  and,  after  infancy  is  passed,  is  still  an  excellent 
article  of  diet.    In  sickness  it  is  often  used  with  advantage 
as  the  sole  nutriment. 

11,  Man's  ordinary  diet  consists  of  meats  (including  fish 
and  eggs),  starchy  foods,  sugar,  and  fat. 

MEATS. 

12,  Of  meats,  there  are  many  kinds.     The  appetite  is 
gratified,  and  the  body  better  nourished,  by  a  variety. 
Beef  is  the  best.     Pork  is  the  staple  meat-food  of  large 
numbers  of  people.     It  is  not  so  wholesome  as  beef,  for 
two  reasons :  — 

1.  It  commonly  contains  a  great  deal  of  fat,  —  too  much 
for  constant  use. 

2.  It  is  more  likely  than  beef  or  mutton  to  contain  the 
young  of  the  tapeworm,  and  oi\\e?  parasites. 

Veal  is  tender  and  good,  but  not  so  easily  digested  as 
beef,  nor  is  it  so  nourishing.  Lamb  is  very  easily  digested. 
Mutton  is  more  nourishing  than  either  lamb  or  veal,  and 
is  nearly  as  good  food  as  beef.  To  some  stomachs,  how- 
ever, it  is  not  acceptable.  Each  of  the  various  kinds  of 
game  has  its  peculiar  flavor,  but  they  do  not  differ  much 
in  nutritive  value. 


80  THE  HUMAN  JiODV. 

All  meat  is  better  and  more  tender  for  being  kept  for  a 
time  after  killing. 

13,  Fish,  on  the  other  hand,  is  better  when  perfectly 
fresh.     It   does   not   differ  very  much  from   flesh  in  its 
chemical  composition ;  though  it  contains  more  water,  and 
less  fat.     It  is  lighter  and  less  stimulating  than  flesh. 

14,  Of  shell-fifth,  oysters  occupy  the  first  place.      They 
are   palatable,  light,   and   nourishing.     They   tempt   the 
appetite  of  an  invalid  without  distressing  his  stomach. 
In  spring  and  early  summer,  they  should  not  be  eaten. 

15,  Lobsters,   crabs,    and    shrimps    are    less    digestible. 
Vinegar  and  stimulating  spices  are  commonly  added  to 
them,  which  spur  up  the  stomach  to  its  task.    They  should 
be  avoided  by  invalids. 

16,  Eggs    contain   much   nourishment,   solidly  packed 
away  for  the  support  of  the  young  fowl  before  he  breaks 
out  of  his  shell.     They  are  palatable,  and  easily  digested. 

STARCHY    POODS. 

17,  The  starchy  foods  include  all  the  grains  —  wheat, 
oats,  corn,  etc.  —  and  vegetables. 

Dried  wheat  contains,  in  100  parts,  66  parts  of  starch. 

Dried  oats  contain,  in  100  parts,  60  parts  of  starch. 

Dried  rice  contains,  in  100  parts,  88  parts  of  starch. 

When  we  remember  that  many  millions  of  the  human 
family  live  chiefly  on  rice,  whose  solid  substance  is  almost 
all  starch,  we  have  good  proof  of  the  importance  of  starchy 
food. 

18,  Besides  starch,  the  grains  contain  mineral  matters, 
fat,  sugar,  and  a  substance,  similar  in  chemical  composition 
to  meat,  called  gluten. 

Wheat  is,  on  the  whole,  the  most  valuable  of  the  grains 


FOOD  AND    WATER,    STIMULANTS,    ETC.  81 

as  food ;  and  men  prefer  it  when  they  can  get  it.  But  each 
grain  has  its  own  advantages.  Corn  is  rich  in  oil.  Oats 
have  much  mineral  matter,  and  much  fibrous,  branny 
substance,  which  make  them  indigestible  for  some  delicate 
stomachs.  For  the  majority  they  are  healthful.  It  has 
been  claimed  that  ground  wheat  is  better  food  with  the 
bran  in  it,  —  in  which  condition  it  is  called  graham  flour, 
—  than  when  the  bran  has  been  separated  from  it,  and  it 
has  been  made  into  fine  flour.  In  sifting  out  the  bran,  we 
take  away  a  good  deal  of  nutritive  substance;  and  what  is 
left  is  chiefly  the  starch.  The  advocates  of  this  view  were 
numerous  a  few  years  ago,  and  were  called  Grahamites,  after 
their  leader  Graham.  Nevertheless,  fine  white  flour  is  still 
the  choice  of  the  majority.  It  is  true  that  much  nourish- 
ment is  lost  in  the  bran.  But  it  is  so  mingled  with  woody 
matters,  that  it  is  not  easily  extracted  by  the  stomach. 
For  healthy  people,  it  is  better  to  use  white  flour,  and 
to  get,  in  other  and  more  digestible  foods,  what  is  con- 
tained in  the  bran.  But  a  stomach  that  is  sluggish  in  its 
action,  is  stimulated  and  aided  by  the  presence  of  the  bran. 
For  such,  graham  flour  is  excellent  food. 

19,  The  potato  is  the  most  popular  of  all  vegetables, 
though  it  has  not  been  in  common  use  more  than  three 
hundred  years.  It  has  been  estimated  that  it  forms  at 
least  three-fifths  of  the  food  consumed  in  Ireland.  Its 
chief  solid  ingredient  is  starch.  Much  of  the  starch  used 
in  the  laundry  is  extracted  from  potatoes.  It  is  superior 
to  other  vegetables  in  being  drier,  and  containing  less 
fibrous  substance. 

20. .  Pease  and  beans  contain  very  little  water,  and  a 
great  deal  of  solid  matter.  They  are  very  nutritious,  and 
are  most  valuable  for  feeding  armies,  and  other  large 


82 


HUMAN    BODY. 


bodies  of  men,  because  they  contain  so  much  in  small 
bulk.  But,  because  they  are  so  solid,  it  is  hard  for  the 
stomach  to  digest  them. 

21.  Tivrnips,  beets,  cabbages,  and  other  garden  vegetables, 
contain  more  water  and  less  nutritive  matter  than  those 
already  referred  to.  They  form  an  agreeable  and  health- 
ful addition  to  more  nutritious  articles. 


SUGAR. 

22,  There  are  many  kinds  of  sugar,  all  sweet,  but 
differing  in  taste  and  solubility.  Most  of  our  vegetable 
food  contains  sugar,  and  a  great  deal  of  pure  sugar  is  used 
in  addition  to  this.  It  is  especially  pleasing,  to  the  taste. 
The  fact  that  children  are  so  fond  of  it,  is  a  proof  that  it 
lias  important  uses  in  the  growing  period.  But,  if  too 

much  is  eaten,  it  spoils 
the  appetite  and  diges- 
tion, and  injures  the 
health. 

FAT. 

23.  Most  vegetable,  as 
well  as  animal,  foods  con- 
tain some/a^.  It  is  cus- 
tomary to  add  oils,  or 
fats  of  some  k  ind ,  to  otl  \  er 
food.  It  is  itself  nutri- 
Flgt36.  tious,  and  aids  in  the 

A  DROP  OF  MILK  MAGNIFIED,  SHOWING  THE     digestion  of  other  tilings. 
OIL-GLOBULES. 


If  we  look  at  a  drop  of  milk  with  a  microscope,  we  see  in- 
numerable little  particles  of  oil.    Oil  is  lighter  than  water; 


FOOD  AND    WATER,    STIMULANTS,   ETC.  83 

and,  therefore,  if  milk  is  allowed  to  stand,  the  oil  will  rise 
to  the  surface,  making  the  cream.  After  the  cream  is 
taken  off,  the  milk  looks  thinner  and  more  transparent. 
If  all  the  cream  could  be  removed  from  it,  it  would  be 
clear,  like  water.  In  making  butter,  the  milk  is  churned 
until  all  the  oily  particles  are  stuck  together  in  a  mass, 
and  the  watery  part  is  separated :  this  latter  is  called 
buttermilk. 

COOKING. 

24.  Animals  eat  their  food  raw.    Men,  even  the  most  un- 
civilized, cook  much  of  it.     Cooking  is  useful  in  three  ways. 

L  It  renders  food  more  digestible, 
z.  It,  kills  parasites  in  meats,  and  stops  putrefaction. 
s.  It  creates  flavors  which  are  attractive,  and  stimulating 
to  the  digestion. 

25.  Raw  meat  is  not  unpalatable:  a  fondness  for  it  is 
often  acquired.     A  disease  called  trichinosis  is  caused  by 
eating  pork,  which  contains  a  minute  worm  called  a  trich- 
ina.    This  worm  can  not  be  recognized  in  pork  without 
a  microscope.     It  is  killed  by  cooking:  smoking  is  not 
sufficient.     The  disease  is,  therefore,  found   only  among 
those  who  have  eaten   raw  pork.     Tape-worms  are  also 
acquired  by  eating  raw  pork  and  beef. 

26.  We  can  not  digest  starchy  foods,  such  as  the  grains 
and  vegetables,  in  sufficient  quantity,  unless  we  cook  them. 
By  cooking,  we  soften   them  so  that  they  can  be  easily 
separated  into  fragments,  and  dissolved  by  the  digestive 
juices.     Besides,  we   add    to   them,   in   cooking,   various 
articles,  such  as  salt,  fat,  sugar,  and  spices,  which  improve 
their  taste.     Flour  is,  in  this  way,  made  into  bread,  and 
cake,  and  pastry  of  many  kinds. 


84  THE   HUMAN   JIODY. 

27,  The  essential  points  for  making  good  bread  are, — 
/.  Good  flour. 

2.  Thorough  kneading,  to  mix  all  the  ingredients. 

s.  Good  yeast. 

4-  Good  judgment  exercised  in  keeping  the  rising  mass 
just  warm  enough,  and  letting  it  rise  just  long  enough. 

5.  Having  the  oven  just  hot  enough,  and  taking  out  the 
bread  at  just  the  right  time. 

28,  Good  bread  is  light  and  sweet.     Bread  is  light  when 
the  carbonic-acid  gas  formed  in  the  fermentation  caused 
by  the  yeast  has  penetrated  the  whole  loaf,  making  in- 
numerable holes  and  pores  in  it.      When  such  bread  is 
eaten,  the  digestive  juices  easily  enter  these  pores,  and 
spread  through  and  act  upon  every  part. 

Bread  is  heavy  when  carbonic-acid  gas  has  not  pene- 
trated the  mass,  either  because  the  yeast  is  poor,  or  the 
flour  is  poor,  or  because  it  has  not  been  thoroughly 
kneaded.  It  makes  a  solid  lump  in  the  stomach,  which 
the  digestive  juices  can  not  easily  enter;  and  that  organ 
becomes  weary  and  sore  in  struggling  with  it, 

Bread  may  be  sour,  either  because  there  is  too  much 
yeast  in  it,  or  because  fermentation  has  gone  on  too  long. 
In  that  case,  acetic  acid  is  formed  in  it. 

29,  Pastry   and   cake  are  not  so  wholesome  as  bread. 
They   please   the   taste,   and    in   small  amounts  are  not 
injurious.      Pie-crust  is  not  commonly  so  light  as  bread. 
Besides,  it  has  a  good  deal  of  lard  or  butter  thoroughly 
mixed  with  it.    This  fatty  matter,  which  is  not  acted  upon 
by  the  juices  of  the  stomach,  coats  over  the  particles  of  the 
flour,  and  prevents  the  gastric  juices  from  reaching  them; 
so  they  must  pass  out  into  the  small  intestine  undigested. 
This  is  the  reason  why  all  food  fried  in  fat  is  less  easily 


FOOD   AND    WATER,    STIMULANTS,   ETC.  85 

digested  than  food  cooked  in  other  ways.  In  the  process 
of  frying,  the  fat  is  so  thoroughly  mixed  with  the  food,  that 
it  renders  it  partly  proof  against  the  stomach-juices. 

Cake  contains  too  much  sugar  and  butter,  in  proportion 
to  its  other  nutritive  matters,  to  be  wholesome  in  large 
quantities. 

30.  Cookery  is  an  art  which  is  very  important  to  health 
and  comfort.     It  must  be  learned  by  practice.     But  those 
who  understand  the  principles  of  chemistry  and  physi- 
ology, on  which  it  rests,  will  acquire  it  more  readily,  and 
be  more  completely  masters  of  it. 

MINERAL   SUBSTANCES. 

31.  Mineral  substances  are  mingled  with  all  our  food. 
Salt  is  the  only  solid  mineral  matter  that  we  take  pure. 
It  enters  into  every  part  of  the  body,  solid  or  fluid,  and 
aids  the  processes  of  life. 

Mineral  matters  are  not  commonly  changed  by  digestion. 

WATER. 

32.  Water  forms  about  seventy  of  every  hundred  parts 
in  the  body.     It  must  be  constantly  supplied,  therefore,  to 
make  up  for  the  waste  of  the  parts.     Digestion,  absorp- 
tion,  and   circulation   would  stop  without  water.     The 
craving  for  it  is  stronger  than  for  food. 

33.  Waters  used  for  drinking  always  contain  a  small 
portion  of  mineral  salts,  of  gases,  and  of  vegetable  mat- 
ter.    Water  which  is  absolutely  pure — as  only  distilled 
water  is  —  is  flat  and  tasteless.     The  mineral  matters  in 
drinking-waters  are  such  as  are  not  harmful  to  the  sys- 
tem, unless  there  is  too  much  of  them.     In  that  case,  they 
are  irritating  to  the  bowels  and  kidneys.     When  water  is 


THE  HUMAN  BODY. 


carried  through  lead  pipes,  it  sometimes  dissolves  enough 
of  the  lead  to  become  poisonous.  Whether  it  will  do  this, 
or  not,  depends  on  what  it  already  contains.  Some 
waters  may  be  carried  through  lead  pipes  with  perfect 
safety,  either  because  the  water  does  not  act  on  the  lead 
at  all,  or  because  it  contains  certain  mineral  matters 
which  form  a  crust,  lining  the  pipes,  and  protecting 
them  from  further  action.  When  lead  pipes  are  used, 
the  question  whether  the  water  acts  upon  them,  should 
be  settled  by  a  chemist  if  necessary.  Tin  pipes  are  safer. 
Water  that  is  constantly  running  through  lead  pipes  is 
less  likely  to  contain  much  lead  than  that  which  stands 
still  in  the  pipes  for  long  periods  without  change.  Lead, 
when  taken  in  small  doses  in  this  way,  produces  its 
effects  very  gradually ;  and  the  health  is  often  seriously 
affected  before  the  cause  is  discovered.  Among  the  symp- 
toms of  lead-poisoning  are  colic,  and  paralysis  of  certain 
muscles. 

34.  Offensive  and  poisonous  matters,  animal  and  vege- 
table, sometimes  find  their  way  into  drinking-water,  and, 
being  dissolved  in  it,  give  no  sign  of  their  presence. 
Sewage,  and  the  germs  of  disease,  may  thus  be  taken  in. 
It  is  necessary,  therefore,  to  guard  the  well,  or  water-pipes, 
very  carefully  from  all  impurities.  Wells  and  reservoirs 
are  often  placed  where  they  catch  the  drainage  from  barn- 
yards, or  other  receptacles  for  filth.  Such  drainage  will 
go  through  the  soil  much  farther  than  is  commonly  sup- 
posed. The  fact  that  water  is  clear  and  sparkling  and 
odorless  does  not  prove  it  pure.  A  well  or  reservoir 
should  not  be  located  within  thirty  feet  of  any  filthy  spot. 
Even  at  that  distance  it  is  not  safe  if  the  ground  is  porous, 
and  slopes  toward  the  well. 


FOOD  AND    WATER,    STIMULANTS,   ETC.  87 

Aqueduct-pipes  sometimes  become  leaky,  and  draw  in 
filth.  Constant  watchfulness  against  the  foes  to  health, 
which  would  enter  in  this  way,  is  necessary. 

BATING   AND    DRINKING   HABITS. 

35,  The  eating  and  drinking  habits  of  mankind  vary 
greatly.     They  are  modified  by  climate  and  by  surround- 
ings.     The   Esquimaux  drink   fish-oil   and  eat   candles 
with  a  relish ;  the  Hindoo  lives  upon  rice ;  the  Arab  sup- 
ports life,  and  performs  great  journeys,  on  a  handful  of 
grain  a  day.     The  European  or  American  requires  more 
and  better  food.     The  human  body  can  adapt  itself  won- 
derfully to  its  circumstances.     But  those  nations,  which, 
by  reason  of  their  geographical  situation  and  their  wealth, 
have  been  able  to  obtain  the  best  and  most  varied  diet, 
have  the  best  and  strongest  bodies. 

36,  There  is  also  a  great  variety  in  the  habits  and  tastes 
of  members  of  the  same  race  or  community.     Some  pre- 
fer one  kind  of  food,  and  some  another.     Some  eat  two 
meals,  and  some  three.     Constitutions,  habits,  and  circum- 
stances make  great  differences.     One  man  may  thrive  on 
food  that  would  destroy  another.     A  brain-worker  may 
accomplish  most  and  feel  best  if  he  eats  little  until  noon: 
a  day-laborer  would  lose  his  vigor  under  such  a  practice. 
One  man  is  over-stimulated  by  a  meat-diet :  another  ought 
to  live  chiefly  on  meat. 

If  Nature  had  not  made  mankind  capable  of  such  vari- 
ations in  habit,  the  work  of  the  world  could  not  be  done. 

37,  A  healthy  appetite  is  Nature's  guide  to  right  habits 
of  eating  and  drinking,  but  Nature  intended  that  appe- 
tite should  be  controlled  and  regulated  by  reason.     Each 
man  will  thus  adopt  that  course  which  is  best  for  him. 


88  THE  HUMAN  BODY. 

38,  When  large  bodies  of  men  have  to  be  fed,  as  in  the 
army  or  navy,  it  becomes  necessary  to  find  out  just  how 
much  of  each  kind  of  food  a  man  requires  daily.  By 
combining  physiological  reasonings  with  experiment,  Pro- 
fessor Dalton  found,  that  for  a  man  in  health,  taking  free 
exercise  in  the  open  air,  the  following  was  a  sufficient 
daily  ration :  — 

Meat  .        .        .        ...        .        .        .16  ounces. 

Bread 19       " 

Butter 8£     " 

Water 52      " 

Total,  water,  3£  Ibs. ;  solids,  2  Ibs.  G£  ounces. 

Men  at  hard  labor  require  more,  and  those  who  are  en- 
tirely inactive,  less. 

STIMULANTS    AND    NARCOTICS. 

SECTION  II.  —  1.  Stimulants  are  substances  which  excite. 
Narcotics  are  substances  which  benumb  and  stupefy.  Some 
substances  are  both  stimulants  and  narcotics.  Alcohol,  if 
taken  in  small  quantity,  is  a  stimulant:  in  large  quantity 
it  is  a  narcotic. 

2,  Nature  supplies  us  with  certain  food-stimulants  which 
are  useful.  Stimulant  is  from  a  Latin  word,  stimulus,  mean- 
ing a  goad.  These  substances  afford  little  or  no  nourish- 
ment, but  they  goad  the  appetite  and  the  digestive  organs 
to  greater  activity.  Such  are  pepper,  spice,  and  mustard. 
Though  good  in  moderation,  they  may  be  used  in  such 
quantities  as  to  injure  the  stomach,  and  make  the  body 
liable  to  various  disorders. 


FOOD  AND    WATER,    STIMULANTS,   ETC.  89 


TEA   AND    COFFEE. 

3,  Tea  and  coffee  are  used  by  all  civilized  nations.    Their 
immediate  effect  is  cheering.     They  often  aid  digestion. 
They  satisfy  the  cravings  of  the  stomach,  and  enable  men 
to  endure  hardship  better.     But  many  persons  are  injured 
by  them, — some,  because  they  drink  too  much;  others,  be- 
cause they  are  too  susceptible  to  their  action.    The  morning 
cup  of  coffee  is  often  paid  for  by  a  daily  headache.     There 
are  intemperate  tea-drinkers.     Tea  contains  a  good  deal 
of  tannin,  which  has  a  tendency  to  check  the  action  of 
the  stomach  and  bowels.     Tea  made  as  the  Chinese  make 
it,  by  simply  pouring   boiling  water   on  the  leaves,  and 
not  steeping  long,  contains  more  of  the  delicate  flavors, 
and  less  of  the  tannin,  than  that  which  is  boiled  for  some 
time.     The  fact  that  some  healthy  people  can  not  go  to 
sleep  at  the  usual  time  if  they  take  a  cup  of  tea  in  the 
evening,  shows  that  it  has  a  decided  effect  on  the  nerves. 
Fretfulness  and  irritability,  and  palpitation  of  the  heart, 
are  results  of  its  immoderate  use. 

4,  Coffee,  as  ordinarily  made,  contains  more  solid  mat- 
ter than  tea,  and  is,  therefore,  more  nourishing.     It  has 
less  of  the  astringent   principle,  and   is   more   soothing. 
Both  tea  and  coffee  will  sometimes  relieve  headache. 

It  is  necessary  that  the  stomach  should  be  very  warm 
in  order  to  digest  well.  If  food  is  taken  cold,  or  if  the 
whole  body  is  in  a  chilly  state,  the  cup  of  tea  or  coffee 
awakens  the  stomach  to  activity  by  conveying  heat  in  an 
agreeable  form. 

5,  Growing  cJnldren  should  drink  neither  tea  nor  cof- 
fee.     Their   fresh   and    vigorous    bodies   need   no   other 
stimulants  than  air,  exercise,  and  simple  food.     They  are, 


90  THE  HUMAN  BODY. 

besides,  much  more  susceptible  than  grown  persons  to  the 
bad  effects  of  these  things. 

TOBACCO. 

6.  Tobacco  is  a  drug  of  very  great  power.     A  drop  of 
the  oil  extracted  from  it,  placed  on  the  tongue  of  a  dog, 
will  kill  him  almost  as  quickly  as  prussic  acid.     It  is 
occasionally  used  as  a  medicine,  but  with  caution,  because 
its  effects  are  so  severe. 

Its  odor  and  taste  are  disagreeable.  When  taken  for 
the  first  time,  it  causes  intense  nausea  and  wretchedness. 
By  persisting  in  its  use,  the  revolt  of  nature  is  commonly 
overcome,  and  a  liking  for  it  is  acquired.  Its  immediate 
effect  is  then  a  feeling  of  tranquillity  and  comfort.  Sol- 
diers and  sailors,  and  others  who  have  to  endure  great 
physical  labors,  find  in  it  support  and  relief.  Students 
use  it  because  it  gives  them  a  freer  flow  of  ideas;  men  of 
pleasure,  because  it  causes  agreeable  sensations.  In  some 
cases  it  seems  to  do  no  harm :  in  others,  its  bad  effects  are 
easily  seen. 

7.  It   diminishes   the   appetite  for   food.     It   sometimes 
causes  disease  of  the  mouth  and  throat.     It  weakens  the 
stomach.     It   becomes   an  absolute  necessity:   brain  and 
stomach  demand   it.     Often  the  amount  used  must   be 
increased  until  it  is  hardly  ever  out  of  the  mouth.     At 
first  soothing  the  nerves,  it  at  last  makes  them  irritable 
and  unsteady. 

8.  Its  effect  on  the  heart  is  so  marked,  that  the  term 
"smokers'  heart"  is  well  known  to  physicians  as  indicating 
irregular  and  weak  action.     The  student  whose  brain  is 
rendered  more  active  by  it,  may  find  himself  suffering  at 
length  from  head-troubles,  and  failure  of  nerve-strength; 


FOOD  AND    WATER,    STIMULANTS,   ETC.  91 

and  he  ends  his  work  before  his  time.  The  business-man 
who  has  gone  beyond  his  natural  powers,  with  the  aid  of 
tobacco,  finally  breaks  down  entirely. 

9,  It  is  evident  that  the  effects  of  tobacco  on  the  young 
are  especially  evil.     Boys  who  use  it  are  dwarfing  their 
minds  and  bodies.     They  are  so  changing  the  system 
from  its  natural  healthy  condition,  that  it  is  preparing 
for  disease,  and  acquiring  tendencies  that  lead  to  dissi- 
pation and  worthlessness.     They  have  no  possible  excuse 
for  its  use. 

10,  Whatever  satisfaction  it  may  give,  is  purchased  at 
the  expense  of  slavery  to  it,  often  of  personal  neatness,  and 
at  the  constant  risk  of  offending  companions  unused  to  it. 
In  some  occupations  it  is  a  serious  hinderance  to  success. 

OPIUM. 

11,  "Opium"  said  the  great  physician  Boerhaave,  "  is  the 
finger  of  God"    Whoever  has  seen  or  felt  the  cessation  of 
pain  that  seemed  unendurable,  under  its  power,  can  re- 
spond to  his  sentiment.     Rightly  used,  it  is  a  boon:  per- 
verted to  purposes  of  sensual  gratification,  it  is  the  cause 
of  untold  misery. 

12,  Opium  not  only  relieves  pain,  but,  in  small  doses, 
gently  stimulates  the  brain  and  nerves,  making  the  taker 
able  to  endure  and  accomplish  more  than  he  otherwise 
could.     In   larger  doses,  it   induces  a   dreamy  state,  in 
which  he  is  released  from  the  annoyances  of  life,  and 
wanders  freely  on  the  wings  of  imagination.     In  poison- 
ous doses,  a  stupor  comes  on,  in  which   the  breathing 
becomes  slow,  sometimes  not  more  than  two  or  three 
breaths  being  taken  in  a  minute.     The  pulse  is  also  slow 
and  full.    When  this  point  is  reached,  the  slumber  is  likely 


92  THE   HUMAN   BODY. 

to  become  deeper  until  death  ensues.  To  avoid  this,  it  is 
necessary  to  do  every  thing  to  keep  the  drowsy  person 
awake, — to  heat  and  pinch  him,  to  keep  him  on  his  feet, 
and  walking,  to  throw  cold  water  on  him. 

13.  Those  who   acquire  the  opium  habit  become  en- 
slaved to  it.     Its  chains  are  even  stronger  than  those  of 
alcohol.      The  misery  which  the  attempt  to  go  without 
occasions,  overcomes  the  strongest  will.     The  victim  be- 
lieves that  he  will  die,  that  he  is  dying,  and  that  only 
opium  will  save  him;  and,  in  these  circumstances,  those 
apparently  most  conscientious  will  lie  and  deceive  to  obtain 
it.     The  practice  tends  to  kill  truthfulness  in  the  soul, 
and  to  undermine  the  whole  character. 

14.  Opium  has  a  paralyzing  effect  on  the  digestive  appara- 
tus.    It  checks  the  flow  of  digestive  juices,  and  the  action 
of  the  muscular  walls  of  the  bowels.     It  takes  away  the 
appetite  for  food.     In  those  not  habituated  to  it,  it  com- 
monly causes  nausea.     When  not  under  its  influence,  the 
opium-taker  suffers  from  headache  and  depression.     His 
nerves  are  relaxed,  his  mind  dull,  and  his  will  feeble.     He 
is  unfitted  for  the  work  of  life,  and  his  only  object  is  to 
gratify  his  craving. 

15.  Opium  should  never  be  taken,  except  under  the  direc- 
tion of  a  physician.     Those  who  are  suffering  from  pains 
which  are   likely  to  return  and  visit   them   frequently, 
should  avoid  it.      It  is  better  to  endure  pain   than   to 
become  a  victim  of  the  opium  habit. 

ALCOHOL. 

16.  Alcohol  can  be  made  out  of  any  thing  that  contains 
sugar.     It  is  only  necessary  to  add  yeast,  or  to  allow  it  to 
stand  uncovered  in  a  warm  place.     In  raising  bread,  the 


FOOD    AND     WATER,     STIMULANTS,    ETC.  93 

sugar  which  is  contained  in  the  flour  is  changed  into 
alcohol  and  carbonic-acid  gas.  This  is  fermentation. 
But  the  heat  of  the  oven  causes  the  small  portion  of 
alcohol  to  evaporate.  The  carbonic-acid  gas,  after  puffing 
up  the  loaf,  and  making  it  light,  also  disappears. 

17.  Wines  are  the  fermented  juice  of  grapes.     They 
contain   from   five   to   twenty-five   per   cent    of    alcohol. 
Brandy,  rum,  whisky,  and  gin  are  distilled  liquors,  and 
are  about  half  alcohol.     Beer,  ale,  and  porter  are  made 
from  grain,  and  have  from  three  to  eight  per  cent  of 
alcohol.      Cider  is  made   of   apple-juice,   and   has   from 
three  to  ten  per  cent  of  alcohol.     The  home-made  wines, 
from  currants,  gooseberries,  -and  elderberries,  contain  a 
small  percentage  of  alcohol. 

18.  Wines  and  liquors  are  very  commonly  adulterated. 
The  pure  article  is  costly.     Some  of  the  substances  used 
are  cocculus  indicus,  alum,  aloes,  copperas,  sulphuric  acid, 
nux  vomica  or  strychnine,  jalap,  and  lime.     By  adding 
certain  substances  to  an  inferior  wine,  or  even  to  alcohol 
and  water,  the  taste  and  effect  of  good  wine  can  be  imi- 
tated, and  a  large  profit  made.     Beer  and  porter  are  also 
sometimes  adulterated,  to  modify  their  flavor,  and  cheapen 
their  manufacture. 

19.  Alcoholic  drinks  cause  a  flushing  of  the  skin  and 
a  feeling  of  warmth.     But  they  do  not  maintain  the  heat 
of  the  body :  they  rather  lessen  it.     This  has  been  proved 
by  careful  experiments,  and  by  the  experience  of  travelers 
in  the  arctic  regions. 

They  check  the  waste  and  repair  that  are  naturally  going 
on.  This  may  be  at  times  an  advantage,  —  in  a  wasting 
disease,  for  example.  But  in  health  it  is  much  better 
that  the  natural  processes  should  be  undisturbed. 


94  THE  HUMAN  BODY. 

20.  Athletes  who  are  training  for  hard  trials  of  their 
bodily  vigor,  abstain  from  alcohol  and  tobacco.     Disease, 
early  failure  of  strength,  and  premature  death,  are  the 
results  of  drinking-habits.      Physicians,  insurance  com- 
panies, and  all  observing  men,  testify  to  this. 

21.  It  is  not  always  true  that  the  strong  liquors  are 
most  pernicious,  nor  that  the  milder  drinks  are  compara- 
tively harmless.     In  some  sections  of  this  country,  cider 
is  a  worse  evil  than  whisky.     Its  apparent  harmlessness 
attracts  those  who  would  refuse  stronger  liquors.     When 
the  appetite  for  this  drink  is  awakened,  it  requires  for  its 
satisfaction  an  amount  of  soaking  that  keeps  the  faculties 
benumbed,  and  reduces  the  individual  to  worthlessness 
as  surely  as  more  fiery,  but  less  abundant,  potations. 

22,  It  is  a  melancholy  fact,  that  "the  evil  that  men  do," 
in  this  regard,  "  lives  after  them."     The  iniquities  of  the 
fathers  are  visited  upon  the  children.     By  an  inflexible 
law  of  nature,  the  effects  of  alcohol  are  not  expended  upon 
the  user  alone.     Morbid  cravings  for  drink,  tendencies 
to  disease,  weakness  of  body  and  mind  and  character, 
are  the  heritage  of  misery  which  he  bestows  upon  his 
offspring. 

23,  Chloral  is  a  drug  of  great  value  in  the  hands  of  the 
physician.     It  gives  sleep  to  those  who  can  not  sleep  in 
the  natural  way.     But  it  is  dangerous.     It  has  caused 
death.     A  habit  of  using  it  may  be  acquired  which  is 
very  injurious  to  body  and  mind,  and  very  difficult  to 
break. 


FOOD  AND    WATER,    STIMULANTS,   ETC.  95 


QUESTIONS. 

SECTION  I.  —  1,  What  is  food  ? 

2,  What  kinds  of  material  are  necessary  for  the  repair  of  the 
body  ? 

3,  How  many  elements  are  found  in  the  body?    Name  them. 
Give  the  number  of  parts  in  a  hundred  of  the  four  most  abundant. 

4,  Name  two  elements  which  are  found  in  almost  every  article 
of  food. 

5,  Do  we  need  in  our  food  any  other  elements  than  the  fifteen 
contained  in  our  bodies  ? 

6,  Where  are  these  fifteen  elements  found?    Name  a  great  dis- 
tinction between  plants  and  animals. 

7,  What  is  the  great  work  of  plants  ? 

8,  Are  all  plants  food  for  man?    Why  not? 

9,  What  do  we  infer  as  to  man's  food  from  his  teeth  ? 

10,  What  article  of  food  is  the  best  combination  of  the  necessary 
elements? 

11,  Of  what  does  man's  ordinary  diet  consist? 

12,  Of  meats,  which  is  the  best?     What  objection  is  there  to 
pork?    Wliat  is  the  value  of  veal  as  food?    Of  lamb?    Of  mutton? 

13,  How  does  fish  differ  from  flesh  ? 

14,  Which  are  the  best  of  the  shell-fish  ? 

17.  What  are  included  in  the  term  "  starchy  foods  "  ?    How  many 
parts  of  starch  in  a  hundred  of  dried  wheat?    Of  dried  oats?    Of 
dried  rice  ? 

18.  What  do  the  grains  contain  besides  starch  ?    What  are  the 
advantages  of  the  different  grains  ? 

19.  What  is  the  most  popular  vegetable? 

20.  Why  are  pease  and  beans  valuable  ? 

22.  Is  sugar  useful  as  a  food  ? 

23.  Wliat  is  butter  ? 

24.  What  is  the  use  of  cooking  ? 

25.  What  is  the  danger  in  eating  meat  raw  ? 

26.  What  gain  is  there  in  cooking  starchy  foods  ? 

27.  What  are  the  essential  points  for  good  bread  ? 

28.  What  makes  bread  light  f    What  makes  bread  heavy  ?    What 
makes  bread  sour  ? 


90  THE   HUMAN   BODY. 

29,  Why  is  not  pie-crust  as  digestible  as  bread?    Why  is  food 
fried  in  fat  indigestible? 

31,  What  mineral  do  we   take   pure  ?      Are    mineral    matters 
changed  by  digestion? 

32,  What  is  the  proportionate  amount  of  water  in  the  body  ? 

33,  Is  drinking-water  ever  absolutely  pure?     What  sometimes 
happens  to  water  which  is   carried  through  lead  pipes?     What 
kinds  of  pipes  are  safer?    What  are  symptoms  of  lead-poisoning? 

34,  How  far  must  a  well  be  from  all  filth  to  be  safe?    Is  it  always 
safe  at  that  distance  ?    How  may  aqueduct-pipes  become  dangerous  ? 

35,  Can  the  body  adapt  itself  to  different  habits  of  eating  and 
drinking  ? 

36,  Do  the  same  rules  for  eating  and  drinking  always  apply  to 
all? 

37,  What  is  nature's  guide  to  right  habits  of  eating  and  drinking? 
Is  the  appetite  always  healthy  ? 

38,  Under  what  circumstances  is  it  necessary  that  a  large  num- 
ber of  people  should  adopt  the  same  habits  of  eating  and  drinking? 
What  is  a  sufficient  amount  of  food  daily  for  a  man  ? 

SECTION  II.  —  1,  What  are  stimulants?    What  are  narcotics ?    Is 
the  same  thing  ever  both  a  stimulant  and  narcotic? 

2,  What  service  does  a  stimulant  render  in  digestion  ? 

3,  What  is  the  immediate  effect  of  tea  and  coffee?    Are  they 
ever  injurious? 

5,  Should  growing  children  use  them  ? 

6,  What  is  the  first  effect  of  tobacco  ?    What  are  its  later  effects  ? 

7,  What  is  its  effect  on  the  appetite  ?  on  the  stomach  ?    On  the 
nerves  ? 

8,  What  is  its  effect  on  the  heart  ? 

9,  Have  boys  any  good  reason  for  using  tobacco  ? 

11, 12,  What  is  the  effect  of  opium  in  small  doses  ?    In  large 
doses  ? 

13,  What  is  the  effect  of  the  opium  habit  on  the  moral  nature  ? 

14,  What  is  the  effect  of  opium  on  the  digestion  ? 

15,  Under  what  condition  only  may  opium  be  rightly  used  ? 

16,  What  does  alcohol  come  from  ? 

17,  What  is  wine  ?    How  much  alcohol  does  wine  contain  ?    What 


FOOD  ANJ)    WATER,   STIMULANTS,   ETC.  97 

are  brandy,  rum,  whisky,  and  gin?  How  much  alcohol  do  they 
contain?  What  are  beer,  ale,  and  porter?  How  much  alcohol  do 
they  contain?  What  is  cider?  How  much  alcohol  does  it  con- 
tain ?  Do  home-made  wines  contain  alcohol  ? 

18,  How  are  the  purchasers  of  wines  and  liquors  defrauded? 

19,  Does  alcohol  keep  up  the  heat  of  the  body?    What  .is  its 
effect  on  the  processes  of  waste  and  repair  ? 

20,  What  is  the  general  testimony  as  to  the  effects  of  alcohol  on 
the  health  ? 

21,  Is  it  true  that  only  the  stronger  liquors  are  hurtful? 

22,  What  is  the  effect  of  alcohol  on  the  children  of  the  drinker  ? 

23,  Under  what  condition  only  should  chloral  be  used  ? 


98  THE  HUMAN  BODY. 


CHAPTER  VII. 

DIGESTION    AND    ABSORPTION. —THE 
LYMPHATIC    SYSTEM. 

SECTION  I. — 1.  Pood  repairs  the  waste  of  the  body,  and 
keeps  up  life.  If  asked  how  it  is  made  to  do  this,  you 
could  answer,  "  It  is  eaten."  By  that,  you  mean  that  it  is 
taken  into  the  mouth,  and  chewed,  and  swallowed.  But 
if  asked  again,  What  becomes  of  it  after  it  is  swallowed, 
and  how  does  it  get  into  our  bones  and  flesh  and  brains, 
and  keep  every  particle  living,  and  perhaps  growing,  you 
could  not  answer  without  study.  For,  in  health,  we  know 
nothing  about  our  food,  by  our  feelings,  after  it  is  swal- 
lowed. 

2,  If,  however,  we  examine  into  the  matter,  we  find  that 
the  food,  after  being  swallowed,  passes  on  down  a  tube 
which  extends  through  the  whole  length  of  the  trunk,  be- 
ginning at  the  lips.     This  tube  is  the  alimentary  canal. 

3,  The  alimentary  canal  is  about  twenty-seven  feet  long, 
in  a  man.     In  order  to  get  it  into  the  trunk  of  the  body, 
which  is  only  about  two  feet  long,  a  portion  of  it  is  coiled 
up  in  a  mass.     This  portion  we  call  the  bowels. 

4,  Most  of  the  canal  is  about  an  inch  and  a  half  wide. 

SUGGESTIONS  TO  TEACHERS. — 1.  An  emulsion  can  be  made  with  oil  and 
the  white  of  an  egg,  or  with  mucilage  obtained  from  the  druggist's.  This 
can  be  compared  with  a  mixture  of  water  and  oil. 

2.  A  tube  made  of  chamois  leather,  or  a  cone  of  filter-paper,  will  illus- 
trate the  soaking  through  membranes. 


DIGESTION  AND  ABSORPTION. 


99 


In  two  places  it  spreads  out,  as  a  brook  spreads  into  a 
pond.    One  of  these  en- 
largements  is  the  stom- 
ach ;  the  other,  the  large 
intestine. 

5,  One  layer  of  the 
wall  of  the  canal  is  in- 
voluntary muscle.   Part 
of  the  libers  run  length- 
wise, and  part  crosswise; 
and  they  surround  the 
tube. 

6,  The  canal  is  lined 
by    mucous    membrane. 
Mucous  membrane  can 
be  seen  on  the  walls  of 
the  mouth.     It  is  quite 
like  the  skin  in  struc- 
ture, but  differs  in  being 
soft  and  moist  and  red. 
The  mucous  membrane 
lines     the     alimentary 
canal,  and  other  cavities 
in  the  body,  just  as  the 
skin  covers  the  outside. 

7,  We    have    been 
speaking  of  the  alimen- 
tary canal  as  a  whole. 

Different  portions  of  it  .  ***'  37' 

Jr>  ALIMENTARY  CANAL  FROM  THE  (ESOPHAGUS 

have    Special    names.     DOWN.  —  I.  CEBophagns.     2.  Stomach.     3.  Small 

The  first  portion  is  the   inte*tiue-  4'  Large  inte8tiDe- 

mouth.     Then  we  come  to  the  throat;  then  to  the  oesophagus, 


100  THE   HUMAN  BODY. 

or  gullet;  then  to  the  stomach,  which  lies  at  the  lower 
border  of  the  ribs,  in  front ;  then  to  the  small  intestine, 
which  is  twenty  feet  long,  coiled  in  the  lower  part  of  the 
abdomen ;  then  to  the  large  intestine,  which  is  five  feet 
long,  and  ends  the  tube. 

DIVISIONS    OP   THE    ALIMENTARY   CANAL. 

1.  MOUTH.  4.  STOMACH. 

2.  PHARYNX  (Throat).  5.  SMALL  INTESTINE. 
8.  (ESOPHAGUS  (Gullet).  6.  LARGE  INTESTINE. 

8,  Each  of  these  divisions  of  the  canal  has  its  own 
peculiarities,  and  each  has  its  own  part  of  the  work  of  the 
whole  to  do.     This  work  is  called  digestion. 

9,  By  digestion,  we  mean  the  changes  that  take  place  in 
the  food,  as  it  passes  through  the  alimentary  canal,  by 
which  it  is  fitted  to  be  taken  into  the  blood. 

10,  The  need  of  such  changes  is  very  plain.     We  could 
not  imagine  that  the  food,  in  the  condition  in  which  it  is 
eaten,  could  be  taken  into  the  blood.     There  are  no  open- 
ings from  the  canal  into  the  blood-vessels.     Nothing  can 
get  out  of  it  into  the  rest  of  the  body,  unless  it  can  soak 
through  its  walls,  as  water  would  soak  out  of  the  finger 
of  a  glove  if  it  were  poured  into  it.     To  do  this,  the  food 
must  be  dissolved. 

11,  A  lump  of  sugar  or  salt  will  dissolve  in  water;  but 
a  piece  of  meat,  or  a  cooked  egg,  or  oatmeal,  or  many  other 
articles  of  food,  will  not.    All  such  articles  must  be  changed 
in  the  alimentary  canal,  so  that  they  will  dissolve  in  water. 

12,  We  find,  accordingly,  that  from  the  walls  of   the 
canal,  and  from  certain  organs  called  glands  which  lie 
just  outside  of  the  canal,  and  communicate  with  it  by 


DIGESTION  AND  ABSORPTION.  101 

tubes,  juices  are  poured  out,  called  digestive  juices,  which 
mix  with  the  food,  and  make  in  it  the  very  changes  that 
are  required.  These  juices  differ  from  each  other,  and 
come  into  different  portions  of  the  canal.  One  juice  acts 
on  one  kind  of  food,  and  another  juice  on  another  kind. 

13.  The  butter  and  cream,  and  all  the  other  fats,  that  we 
eat,  are  acted  on  in  a  way  peculiar  to  themselves.     They 
are  not  really  made  to  dissolve  in  water;  but  a  juice  is 
furnished,  called  the  pancreatic  juice,  with  which  they 
are  so  thoroughly  mixed,  that  they  will  pass  through  that 
part  of  the  wall  of  the  alimentary  canal  which  is  their 
special  way  out. 

14.  There  are  some  other  fluids,  besides  this  pancreatic 
juice,  that  oil  will  mix  with;  and  such  mixtures  are  called 
emulsions.     Milk  is  an  emulsion.     The  oil-globules  dif- 
fused through  it  rise  to  the  top,  and  make  the  cream ;  and 
from  the  cream  we  make  butter,  by  the  method  already 
described  (Chap.  VI,  Sect.  I.,  23).    We  eat  the  butter.     It 
passes  down,  without  being  changed,  until  it  reaches  the 
place  where  the  pancreatic  juice  comes  in.     With  that  it 
mixes;    and   all   these   little  oil-globules    are    separated 
again,  and  diffused  through  the  fluid,  just  as  they  were  at 
first  in  the  milk.     This  fluid  is  the  chyle;  and  it  looks 
so  very  like  milk,  that  the  little  hair-like  tubes  that  carry 
it  away,  after  it  has  passed  through  the  wall  of  the  canal, 
are  called  lacteals,  or  milk-vessels.     (Latin,  lac,  milk.) 

15.  The  muscle  in  the  walls  of  the  canal  has  a  good  deal 
to  do  with  digestion,  as  well  as  the  juices  inside.     It  acts 
in  two  ways :  it  forces  the  food  along,  and  it  kneads  and 
mixes  it  with  the  juices.     We  know  how  the  muscles  of 
the  mouth  and  throat  close  about  it,  when  we  swallow. 
These  are  voluntary  muscles,  and  we  are  conscious  of  their 


102  THE  HUMAN   BODY. 

action.  When  it  gets  below  the  throat,  the  muscles  are 
still  contracting  around  it  and  behind  it,  pushing  it  on,  as 
we  strip  water  from  a  soft  tube  by  drawing  it  between  our 
ringers.  But  these  are  involuntary  muscles,  and  we  are 
not  conscious  of  their  action.  While  it  remains  in  the 
stomach,  the  muscles  are  constantly  "working"  it,  very 
much  as  a  baker  works  his  bread  to  mix  the  yeast  with 
it.  The  same  processes  continue  through  the  small  and 
the  large  intestine. 

If  the  juices  are  too  scanty,  or  poor  in  quality,  diges- 
tion does  not  go  on  well.  If  the  muscle  of  the  walls  of 
the  canal  is  weak  or  sluggish,  digestion  does  not  go  on 
well.  These  conditions  are  called  dyspepsia. 

16,  AVhat  has  been  said  of  the  changes  in  the  food,  that 
constitute  digestion,  may  be  summed  up  as  follows:   TJie 
fats  are  made  into  a  fine  emulsion.    The  other  kinds  of 
food  are  changed  into  substances  that  easily  dissolve  in 
the  fluids  of  the  canal. 

THE   TEETH. 

17,  Let   us   examine   more   particularly   the   different 
parts  of  the  digestive  apparatus.     Just  behind  the  lips,  the 
outer  gates  of  the  alimentary  canal,  stand  the  inner  gates, 
the  teeth.    A  child  of  about  five  years  of  age,  who  has  not 
yet  lost  any  of  his  first  teeth,  has  twenty  in  all,  ten  in  each 
jaw.     If  we  could  look  deep  into  his  jaw-bones,  we  should 
see,  beneath  these  twenty,  twenty-eight  more, — buds  of 
teeth,  so  to  speak,  which  are  his  second  set  (all  but  four), 
almost  ready  to  grow  out.     So  that,  at  that  age,  a  child 
has  really  forty-eight  teeth,  —  more  than  at  any  other  time 
in  his  life. 

18,  The  first  set  are,  — 


DIGESTION  AND   ABSORPTION.  103 

Eight  incisors  (cutters),  four  front  teeth  above  and 
below. 

Four  canines  (Latin,  canis,  a  dog),  next  to  the  incisors. 

Eight  molars  (Latin,  mola,  a  mill),  grinders,  back 
teeth. 

The  incisors  are  chisel-shaped,  and  intended  for  cutting, 
not  for  chewing. 

The  canines  correspond  to  the  long,  pointed  fangs  of 
a  dog,  and  are  made  for  piercing  and  holding  on  to 
things. 

The  molars  are  broad  and  blunt,  and  are  made  for 
grinding  up  food. 

19,  The  second  set,  the  last  of  which  do  not  appear  before 
the  age  of  seventeen  years,  comprises 

Eight  incisors,  four  front  teeth  above  and  below. 

Four  canines,  next  to  the  incisors. 

Eight  bicuspids,  next  to  the  canines. 

Twelve  molars,  back  teeth. 

The  first  set  come  out,  one  by  one,  between  the  ages  of 
five  and  fourteen  years;  and  the  second  set  appear  one 
by  one  as  the  first  are  lost.  The  wisdom  teeth  are  the 
last  to  appear,  at  some  time  after  seventeen  years  of  age. 

20,  Animals  that  live  wholly  on  flesh,  like  the  tiger, 
have  no  grinders,  but  only  cutting-teeth.     Their  jaws  do 
not  move  from  side  to  side,  but  only  up  and  down,  like 
shears.     On  the  other  hand,  animals  that  live  wholly  on 
vegetable  food  have  many  broad   grinders,  and   not  so 
many  cutting-teeth  in  proportion;  and  their  jaws  have  a 
motion  from  side  to  side,  as  well  as  up  and  down.     Man 
is  well  provided  with  both  kinds  of  teeth,  which  goes  to 
prove  that  lie  was  made  to  live  on  both  vegetable  and 
animal  food. 


104 


THE  HUMAN  BODY. 


Crown.. 


Neck.. 


Root., 


Fig.  38. 


21.  A  tooth  is  made  of  a  substance  like  bone,  called 
dentine.  At  the  end  of  the  root,  a  very  small  hole  can 
be  seen.  This  is  the  entrance  to  a  canal 
which  runs  through  it  lengthwise,  and 
contains  the  tiny  nerve  and  blood-vessel 
which  supply  it.  The  root  is  fixed  in  a 
socket  in  the  jaw-bone.  The  crown,  or 
body,  projects  beyond  the  gums.  The 
neck  is  at  the  junction  of  crown  and  root. 
The  crown  is  covered  by  enamel,  which 
is  the  hardest  substance  in  the  body. 

22,  It  is  the  work  of  the  teeth  to  bite 
off  mouthfuls  of  food  of  the  right  size, 
INCISOR  TOOTH  SAWED  an(j  then  to  grind  them  up  fine.  This 
is  the  first  act  in  digestion.  When  food 
is  well  ground,  the  juices  of  the  stomach  easily  mix  with 
it,  and  act  on  it.  If  the  teeth  are  gone,  or  if  food  is  bolted 
without  being  chewed,  it  enters  the  stomach  in  lumps, 
which  the  juices  can  not  easily  pene- 
trate. When  food  is  not  soon  acted  on 
by  the  digestive  juices,  it  becomes  sour, 
and  makes  gases,  which  distend  the 
stomach,  and  often  give  pain. 

23.  The  teeth  stop  growing  after 
they  have  taken  their  places;  and,  if 
they  are  chipped,  they  do  not  heal. 
They  may  be  injured, — 

i.  By  very  hot  or  very  cold  substances. 
9.  By  some  medicines. 
5.  By  decomposing  food  between  them. 
They  should  be  brushed  every  day,  and  cared  for  by  a 
dentist  if  unsound.     Good  health  and  good  looks  both 
depend  much  on  them. 


Enamel. 


Fig.  39. 

MOLAK  TOOTH  SAWED  IN 
TWO. 


DIGESTION    AND    ABSORPTION.  105 


THE    SALIVARY    GLANDS. 

24,  In  health,  the  mouth  is  always  moist.     When  we 
taste  any  good  thing,  or  even  think  of  it,  the  "mouth 
waters."     This  water  is  the  saliva,  or  spittle ;  and  most  of 
it  comes  from  bodies  called  the  salivary  glands. 

25,  There  are  three  pairs  of  these  glands, — two  parotid 
glands,  two   submaxillary   glands,   and    two   sublingual 
glands. 

The  parotid  gland  is  the  largest,  and  is  situated  just 
under  the  ear.    Mumps  is  an  inflam- 
mation of  this  gland,  which  makes 
it  swell,  and  the  neighboring  parts 
of  the  neck  with  it. 

The  submaxillary  gland  is  next  in 
size,  and  lies  behind  the  edge  of  the 
under  jaw  beneath  the  floor  of  the 
mouth. 

The  sublingual  gland  lies  farther 
forward  than  the  submaxillary,  also  Fi  4Q 

Under  the  floor  Of  the  inOUtll.  A  portion  of  the  Parotid  gland, 

26,  When  these  glands  are  exam-  magnified. 

ined  with  the  aid  of  a  microscope,  they  are  seen  to  consist 
of  tubes,  large  and  small,  with  little  sacs  on  the  end  of 
them.  They  may  be  compared  to  a  mass  of  cherries  on 
a  branch,  or  bunches  of  grapes  pressed  together.  Small 
blood-vessels  penetrate  the  mass,  and  surround  the  tubes 
and  the  sacs.  Water  and  other  substances  pass  from  the 
blood  through  the  walls  of  the  blood-vessels,  and  into  the 
sacs,  to  make  the  saliva.  As  the  sacs  and  tubes  get  full, 
the  saliva  flows  from  the  small  tubes  into  larger  ones,  and 
then  into  still  larger  ones,  and,  finally,  it  is  all  collected 


10!)  THE    II  UMAX     ]}()  fir. 

in  one  large  tube,  which  is  called  the  duct  of  the  gland. 
The  duct  of  the  parotid  gland  opens  on  the  inside  of  the 
cheek.  The  ducts  of  the  submaxillary  and  sublingual 
glands  open  under  the  tongue. 

27,  These  glands  make  the  saliva  from  the  blood  which 
passes  through  them.     The  saliva  moistens  and  softens 
the  mouthful  of  food,  coats  it  over,  so  that  it  will  slip 
down  the  canal,  and  to  some  extent  dissolves  it.     When 
the  mouth  is  absolutely  dry,  it  is  almost  impossible  to 
chew  or  swallow  any  thing. 

THE  STOMACH. 

28,  The  stomach  is  a  portion  of  the  alimentary  canal 
about  twelve  inches  long,  expanded   into  a  pouch.      It 
lies  at  the  lower  border  of  the  ribs  in  front,  more  on 
the  left  side  than  on  the  right.     When  it  is  empty,  it 
collapses,  like  any  other  bag.     When   it  is  full,  it  ex- 
tends down  below  the  ribs ;  and,  as  it  lies  directly  under 
the  heart,  it  sometimes  presses  up,  and  makes  the  heart 
feel  crowded. 

29,  This  pouch,  like  the  rest  of  the  alimentary  canal,  is 
lined  with  mucous  membrane,  somewhat  like  the  lining 
of  the  mouth.     If  this  membrane  is  examined  with  a  lens, 
innumerable  little  holes  appear:  so  small,  and  so  close 
together,  are  they,  that  it  has  been  estimated  that  there 
are  five  millions  of  them  in  all.     These  are  the  mouths 
of  little  pits  that  dip  down  in  the  membrane.     Some  of 
these  pits  are  shaped  like  the  finger  of  a  glove:  others 
have  side-branches,  like  several  glove-fingers  opening  into 
one  central  finger.     These  are  the  glands  of  the  stomach, 
which  make  the  gastric  juice.      When  food   enters  the 
stomach,  this  juice  wells  up  from  the  pits  until  a  drop 


DIGEXTIOX   AND  AliSORPTION. 


107 


Fig.  41. 
STOMACH  GLANDS  op  A  L'i». 


stands  at  the  mouth  of  each  one.  This  overflows,  and 
another  follows;  and  so  it  keeps  coming,  until  there  is 
just  enough  to  mix  with  the  food  taken.  Then  it  stops. 
Meantime  the  muscular  walls  have  been  turning  and 
squeezing  the  food,  some- 
what as  the  teeth  and 
tongue  do  in  the  mouth. 

30.  The   outlet   of  the 
stomach   is    at    its    right 
end,  and   is  guarded   by 
the  pylorus  (from  a  Greek 
word,  meaning  keeper  of 
the  gate).      This  pylorus 
is    a    ring    of    muscular 
fibers,    which    surrounds 
the    canal,  and,  by  con- 
tracting, closes  it.  Its  duty 

is,  to  let  no  food  pass  out  until  it  has  been  properly  acted 
on  by  the  stomach.  When  the  food  is  hard  and  indigest- 
ible, the  laboring  stomach  often  becomes  exhausted  and 
distressed.  It  would  fain  get  rid  of  its  contents :  but  the 
pylorus  steadfastly  resists,  until  vomiting  occurs;  or  else, 
this  resistance  being  overcome,  the  troublesome  matters 
pass  down,  to  cause  similar  discomfort  in  the  intestines. 

31.  Near  the  beginning  of  the  small  intestine,  two  little 
tubes  open  into  it  by  the  same  orifice.     If  we  follow  these 
back  a  short  distance,  one  will  lead  us  to  the  liver,  the 
other  to  the  pancreas. 

THE   LIVER. 

32.  The  liver  is  a  large  organ  situated  at  the  lower 
border  of  the  ribs,  on  the  right  side.     It  is  a  gland,  and  it 
does  three  things:  — 


108 


THE  HUMAN  BODY. 


1.  It  helps  to  purify  the  blood,  by  taking  out  of  it  certain 
substances. 

-&  It  makes  glycogen,  Glycogen  is  a  food  substance,  made 
of  the  food  we  eat,  and  stored  up  for  a  time  in  the  liver, 


Liver. 


Gullet.    Pancreas. 


Small  intestine. 

Fig.  42.     ' 
THE  LIVER  AND  OTHER  ORGANS  op  DIGESTION. 

somewhat  as  starch  is  stored  up  for  the  use  of  a  potato- 
plant  in  the  potato. 

5.  It  makes  bile. 

33,  So  large  an  organ  as  the  liver  must  have  a  very 
important  work.  When  the  flow  of  bile  is  cut  off,  the 


DIGESTION  AND  ABSORPTION.  109 

flesh  is  rapidly  lost,  and  death  ensues.  Sometimes  the 
duct  of  the  liver  gets  clogged.  The  yellow  stream  of  bile 
is  dammed  up,  and  forces  itself  into  the  blood-vessels,  and 
is  carried  all  through  the  body.  It  colors  the  skin  and 
eyes  yellow.  This  condition  is  called  jaundice. 

The  bile  in  the  intestine  mingles  with  the  other  diges- 
tive juices,  and  with  the  food,  and  aids  digestion  in  sev- 
eral ways. 

34,  The  pancreas  lies  across  the  backbone,  just  behind 
the  stomach.     It  is  only  one-twentieth  as  large  as   the 
liver.     It  is  a  mass  of  little  tubes,  in  which  the  pancreatic 
juice  is  forming  during  digestion.      These   little  tubes 
empty  into  one  large  tube,  which  runs  through  its  whole 
length,  and  finally  discharges  into  the  intestine,  just  as 
the  small  drain-pipes  in  the  houses  of  a  town  empty  into 
the  large  main  in  the  street,  and  that,  finally,  into  the 
river. 

35,  The  pancreatic  juice  makes  a  mixture,  called  an 
emulsion,   of   the  fats,   in   which   they  can   easily  pass 
through  the  walls  of  the  canal.     It  also  aids  in  dissolving 
other  parts  of  the  food. 

36,  The  lining  of  the  whole  length  of  the  small  and 
large  intestines  contains  little  pits  similar  to  those  which 
are  found  in  the  stomach.     A  fluid  called  the  intestinal 
juice,  which  helps  digestion,  wells  up  out  of  them;  but 
the  action  of  this  fluid  is  not  so  important  as  that  of  the 
gastric  juice. 

37,  Recapitulation.     The  digestive  apparatus  consists 
of  the  alimentary  canal,  and  certain  glands  connected 
with  it. 


110 


THE   HUMAN   BODY. 


Divisions  of  the  canal, 


f  In  the  canal 


Digestive 
glands, 


Mouth  (containing  teeth  and  tongue). 

Throat. 

Gullet. 

Stomach. 

Small  intestine. 

Large  intestine. 

Stomach  glands,  making  gastric  juice. 

Intestinal  glands,  making  intestinal  juice. 


Outside   the 
canal    . 


making  sa- 
liva. 


Parotid,  1 

Salivary  glands,  \  Submaxillary,  I 

Subliiigual,       J 

Liver,  making  glycogen  and  bile. 
Pancreas,  making  pancreatic  juice. 

ABSORPTION. 

SECTION  II. — 1,  The  alimentary  canal  may  be  likened 
to  the  kitchen  in  which  the  food  is  prepared.  The  blood 
is  the  carrier,  swiftly  moving  through  the  passage-ways, 
and  serving  every  room  in  the  house  of  life. 

2,  Through  the  whole  length  of  the  canal,  its  wall  is 
filled  with  meshes  of  hair-like  blood-vessels,  completely 
surrounding  it,  like  a  net-work,  ready  to  soak  up  the  food 
through  their  thin  walls  just  as  fast  as  it  is  made  ready. 
Through  these  little  vessels  the  current  is  moving,  so  that 
fresh  blood  is  continually  taking  the  place  of  that  which 
has  just  passed  on  with  its  load. 

3.  Let  us  follow  a  mouthful  of  food,  consisting  of  bread 
and  meat,  from  its  entrance  between  the  lips   into  the 
canal.     First  the  teeth  cut  and  grind  it,  the  tongue  and 
cheeks  skillfully  turning  and  shifting  it  from  side  to  side, 
the  saliva,  meantime,  wetting  and  partly  dissolving  it. 
When  it  is  fine  and   soft  enough,  the  tongue  forces   it 
against  the  roof  of  the  mouth,  and  so  slips  it  back  to  the 
throat.     Certain  muscles  then  contract,  and  lift  the  throat 
up  around  it.     It  is  clasped  and  pushed  down  by  the  con- 


DIGESTION  AND  ABSORPTION. 


Ill 


traction  of  successive  rings  of  muscular  fibers,  through 

the  gullet  into  the  stomach.    There  it 

remains  for  a  time.     It  has  not  been 

long  in  the  stomach  before  portions  of 

it  are  digested,  and  these  begin  to  pass 

through  its  walls.     Other  portions  are 

not  digested  by  the  gastric  juice.    But 

the  whole  is  reduced  to  a  fluid-like 

gruel,  and  then   passes   the   pylorus 

into  the  small  intestine.     In  this  state 

it  is  called  chyme.    Here  it  meets  the 

bile  and  the  pancreatic  juice.     These 

mix  with  the  fat,  and  make  an  emul- 
sion which  is  called  chyle.     The  rest 

of  the  food  is  also*changing,  and  being 

dissolved  out  of  the  branny  and  fibrous 

parts  which  can  not  be  digested. 

4,    In  the  lining  of  the  small  intestine,  we  find  a  special 

apparatus  for  absorption;  and  it  is  here  that  absorption 

goes  on  most  actively. 

This  lining  has  a  soft  look, 
like  velvet.  With  a  micro- 
scope we  can  see  that  the 
reason  that  it  looks  so,  is,  that 
it  actually  has  a  nap,  like 
velvet.  This  nap  is  made  of 
innumerable  short,  thread- 
like projections,  which  are 
called  villi  (Latin,  villus,  a 
tuft  of  hair). 

5,    Each  villus  contains  a 

net-work  of  fine  blood-vessels,  and,  also,  one  of  another 


Fig.  43. 

VILLI  or  THE  SMALL  IN- 
TESTINE MAGNIFIED. 


Fig.  44. 
SHOWING  THE  VESSELS  IN  VILLI. 


112  THE   HUMAN  BODY. 

kind  of  vessels  called  lacteals,  which  will  be  described 
presently,  whose  special  work  it  is  to  take  up  fat. 

6,  As  the  muscular  walls  of  the  intestine  contract  and 
relax,  these  little  villi  are  worked  in  the  mass  of  food; 
and  they  draw  in  the  digested  part  as  the  fine  rootlets  of 
a  plant  draw  up  liquid  nourishment  from  the  earth  in 
which  they  stand. 

7,  As  the  chyme  and  chyle  pass  on  down  the  small 
intestine,  the  digestible  portion  is    constantly  growing 
less,  until  at  length  it  has  all  been  taken  up, — the  chyle 
chiefly  by  the  lacteals,  and  the  other  portions  of  the 
food  chiefly  by  the  blood-vessels;  and  what  remains  is 
indigestible  and  useless. 

8,  The  food,  having  thus  become  a  part  of  the  blood,  is 
carried  through  the  body,  and  permitted   to  soak  out 
through  the  walls  of  the  capillary  vessels,  to  feed  each 
particle  of  living  substance. 

9,  Water,  and  mineral  matters  like  salt,  that  are  dis- 
solved in  water,  need  no  digestion,  and  are  taken  up  by 
the  vessels  in  all  parts  of  the  canal. 

SECTION  III.  —  The  lymphatic  system.  1,  This  is  a 
system  of  tubes  and  glands,  —  the  tubes  resembling  the 
blood-vessels  in  some  respects.  They  begin  with  hair-like 
tubes  running  among  the  capillaries,  and  much  like  them. 
These  unite  to  form  larger  tubes,  which  unite  with  others, 
and  so  on,  until  they  have  all  been  united  into  two  tubes, 
each  about  as  large  as  a  slate-pencil.  These  open  into  the 
large  veins,  not  far  from  the  heart.  They  are  called  the 
thoracic  duct  and  the  right  lymphatic  duct. 

2,  But  the  lymphatic  system  is  not  just  like  the  system 
of  blood-vessels.  The  lymph,  as  the  fluid  which  they  con- 


DIGESTION    AND    ABSORPTION. 


113 


tain  is  called,  does  not  "  circulate."  The  blood  starts  from 
the  heart,  and  is  brought  around 
back  to  the  heart  again.  The 
lymph  starts  from  all  parts  of  the 
body,  and  is  brought  in  toward 
the  heart.  If  you  compare  the 
lymphatic  vessels  with  the  capil- 
laries and  veins,  you  have  nothing 
in  this  system  to  correspond  with 
the  arteries. 

The  capillaries  of  the  lymphatic 
system  form  networks  which  are 
interwoven  with  the  networks 
made  by  the  capillaries  of  the  cir- 
culatory system.  Where  the  blood 
capillaries  are  numerous,  the  lym- 
phatic capillaries  are  numerous. 
Where  the  blood  capillaries  are 
wanting,  the  lymphatic  capillaries 
are  wanting.  In  the  skin,  the  net- 
work of  capillary  blood-vessels  is 
spread  out  nearest  the  surface. 
The  network  of  lymphatics  lies  be- 
neath. The  two  sets  of  vessels  are 
always  found  near  together.  This 
would  lead  us  to  suppose  that  they 
worked  together.  When  we  study 
their  action,  we  find  that  they  do. 
But  the  blood-vessels  both  give  to 
the  tissues  from  their  contents,  and 
take  from  the  tissues  their  waste. 
The  lymphatics  give  nothing  to  the  tissues:  they  only 
take  from  them. 


Fig.  45. 

LYMPHATICS.  —  1.  Lymphatic 
ducts.    2.  Lymphatic  glands. 


114 


THE  HUMAN  BODY. 


Aorta> 


The  lymphatic  vessels  are  much  more  delicate  and 
slender  than  the  blood-vessels. 

3.  When  a  farmer  has  a  wet  field,  he  frequently  lays 
pipes  in  it  made  of  burned  clay,  called  tile.     The  standing 
water  soaks  into  these  pipes,  and  is  carried  off;  and  so 
the  field  is  dried. 

The  lymphatics  are  the  drain-pipes  of  the  body.  They 
assist  the  blood-vessels  in  taking  up  the  fluids  which  are 
standing  in  all  parts,  and  carrying  them  away  to  be 
delivered  up  to  the  blood-stream  at  the  proper  place. 

4,  The   lacteals   comprise    that   portion    of   the    lym- 

phatic  vessels  that 
begins  in  the  walls 
of  the  small  intes- 
tine. When  diges- 
tion is  not  going  on, 
they  are  drain-pipes, 
like  the  rest.  As 
soon  as  digestion 
begins,  they  begin 
to  look  white  and 
milky.  They  are 
then  engaged  in 
their  special  work  of 
taking  up  the  fat 
from  the  intestine. 
They  are  found  in 
all  the  villi. 


Thoracic 
\  duct. 


Lymphatic 
glands. 


Small 
intestine. 


Lacteal*. 

Fig.  46. 
LYMPHATICS  OP  THE  INTESTINE. 


SECTION  IV.  —  1.  The  process  of  digestion  is  not  under 
control  of  the  will.  In  health  it  takes  care  of  itself,  and 
we  give  no  thought  to  it.  But,  when  the  digestive  appa- 


DIGESTION  AND  ABSORPTION.  115 

ratus  is  weak  or  disordered,  it  becomes  the  seat  of  almost 
constant  pain  and  discomfort.  The  appetite  is  lost,  the 
strength  fails,  the  nerves  become  irritable,  and  the  brain  is 
clouded.  It  is  important,  therefore,  to  know  what  helps  or 
hinders  it. 

HINDEBANCBS    TO   DIGESTION. 

1.  Eating  too  fast.     In  this  case,  the  food  is  taken  down 
without  being  prepared  by  chewing. 

2.  Strong  excitement.     Sudden  fear,  anger,  or  grief  takes 
away  the  appetite,  and  stops   the  flow  of  the  digestive 
juices. 

s.  Great  fatigue.  No  careful  horse-owner  will  feed  his 
animal  immediately  when  he  comes  in  tired  and  heated. 
Food  swallowed  under  such  circumstances  will  be  digested 
with  difficulty  by  a  man  or  a  horse. 

4-  Mental  effort.  It  is  not  well  to  read,  or  to  study  during 
a  meal.  The  mind  should  be  at  rest,  and  some  degree 
of  attention  should  be  given  to  the  food. 

5.  Too  much  food.     Evidently  there  is  a  limit  to  the 
amount  of  food  that  can  be  digested.     The  stomach  may 
be  so  full  that  it  can  not  easily  move  its  contents.     The 
quantity  may  be  so  great  that  the  digestive  fluids  can  not 
fully  permeate  them.     Those  parts  of  the  mass  which  are 
not  digested  will  soon  decompose,  producing  acidity,  and 
a  pressure  of  gas. 

6.  Too  much  liquid  ivith  food.     A  good  deal  of  water  is 
directly  absorbed.     But,  when  too  much  is  taken,  some 
remains  in  the  stomach,  and  so  dilutes  the  gastric  juice, 
that  it  is  weakened. 

7.  Very  cold  substances,  as  ice-water,  taken  with  food,  will 
sometimes  stop  digestion.     The  gastric  juice  acts  best  in  a 


116  THE  HUMAN  BODY. 

temperature  of  about  a  hundred  degrees.  Stomachs,  how- 
ever, differ  in  their  ability  to  withstand  cold  as  much  as 
the  outer  parts  of  the  body. 

8.  Irregularity   in  eating.      The  digestive  apparatus  is 
subject  to  habit,  like  the  rest  of  the  system.     At  the  ac- 
customed meal-time,  the  saliva  and  the  other  digestive 
fluids  will  flow,  though  no  food  is  taken.    When  that  time 
is  passed,  they  do  not  start  so  readily. 

9.  Lack  of  exercise.     In  a  sluggish  condition  of  the  body, 
the  digestive  juices  flow  slowly.     The  alimentary  canal 
does  not  contract  vigorously  to  knead  the  food. 

10.  In  applying  these  principles,  it  is  to  be  remembered 
that  one  person  can  do  without  harm,  and  sometimes  with 
advantage,  what  is  injurious  to  another.     Men  differ  very 
widely  in  their  habits.      Each   should   understand   the 
facts  and  principles  of  physiology,  and  apply  them,  with 
the  aid  of  experience,  to  his  own  case. 


EFFECTS   OF   ALCOHOL   ON   DIGESTION. 

SECTION  V. — 1.  Alcohol  irritates  the  mucous  mem- 
branes. You  could  not  hold  it  in  your  mouth;  and,  if 
you  should  swallow  any  of  it  clear,  your  stomach  would 
seem  burned.  When  mixed  with  much  water,  as  it 
is  in  wines  and  liquors,  it  is  less  fiery,  and  the  sensa- 
tions produced  in  the  mouth  and  stomach  may  be  agree- 
able. 

2.  It  is  by  this  irritant  quality  that  it  injures  the 
stomach.  In  the  famous  case  of  St.  Martin,  the  inside  of 
whose  stomach  could  be  observed  through  a  wound,  Dr. 
Beaumont  found  that  "  the  free  use  of  ardent  spirits,  wine, 
beer,  or  any  of  the  intoxicating  liquors,  when  continued 


DIGESTION  AND   ABSORPTION.  117 

for  some  days,"  constantly  produced  "a  state  of  inflamma- 
tion and  nlceration  in  the  lining  membrane,  and  change 
of  the  gastric  juice."  At  the  same  time,  St.  Martin  suffered 
no  pain,  or  other  sensations,  which  indicated  the  true  state 
of  things. 

Examinations  of  the  stomachs  of 'drinkers,  after  death, 
show  the  same  conditions. 

3,  One  of  the  most  wonderful  things  about  our  bodies 
is,  that  they  will  change  so  as  to  suit  the  conditions  in  which 
they  are.     If  a  man  has  to  work  with  his  arms,  they  grow 
large  and  strong.     If  the  skin  is  exposed  to  the  weather, 
or  to  chafing,  it  loses  its  smoothness,  and  becomes  hard. 
The  stomach  wras  made  to  digest  wholesome  food.     If  a 
man  insists  on  making  it  a  receptacle  for  burning  liquors, 
Nature  straightway  begins  to  adapt  it  to  that  use.     The 
delicate  membrane  grows  tough.     The  mucus  which  nat- 
urally moistens  it  becomes  thick  and  ropy,  so  as  to  protect 
the  surface.     Some  of  the  little  glands  which  pour  out 
the  gastric  juice  are  destroyed.     Those  which  remain  are 
unhealthy.     If  the  process  is  carried  far  enough,  lie  has  a 
pouch  which  gladly  receives  alcohol,  but  its  usefulness  as 
a  stomach  is  greatly  impaired. 

4,  If  we  put  in  a  test-tube  some  gastric  juice  from  the 
stomach  of  an  animal,  and  add  alcohol  to  it,  a  white 
powder  appears,  and  settles  to  the  bottom.    This  is  pepsin, 
which  gives  the  juice  its  power  to  digest.     Alcohol  sepa- 
rates it  from  the  juice;  so  the  drinker,  with  a  stomach 
perhaps  already  weak,  is  adding  to  his  gastric  juice  that 
which  destroys,  for  the  time,  what  activity  it  has.     After 
the   alcohol   passes   out   of    the  stomach,   the  pepsin   is 
dissolved  again. 

5,  The  effect  of  alcohol  on  the  intestine  is  similar  to 


118  THE  HUMAN  BODY. 

that  on  the  stomach,  but  much  less ;  because  most  of  it  is 
absorbed  before  reaching  that  part  of  the  canal. 

6,  Alcohol  is  carried  to  the  liver  by  the  blood. 
Alcohol  irritates  the  liver,  arid  causes  an  overfullness  of 

its  blood-vessels. 

Alcohol  often  excites  inflammation  of  the  liver.  This 
is  followed  by  various  changes,  one  of  the  most  notable 
of  which  is  a  contraction  into  a  hard,  knobbed  mass, 
called,  in  medical  works,  gin-drinker's  liver. 

7,  Thus  the  power  of  digesting  food,  which  is  the  source 
of  health  and  strength,  is  assailed  by  alcohol  at  two  im- 
portant points,  —  in  the  stomach,  and  in  the  liver. 

8,  The  effect  of  alcohol  on  the  kidneys  may  be  referred 
to  here,  because  it  is  similar  to  its  effect  on  the  liver.    The 
kidneys  are  purifying  organs.     The  blood  is  constantly 
passing  through   them,  and   they  filter  out  of  it  waste 
matters.     Blood  charged  with  alcohol  irritates  them,  and 
excites,  frequently,  a  slow  inflammation,  which  results  in 
their  destruction.     This  is  one  of  the  forms  of  Bright's 
disease,  and  in  most  cases  is  incurable. 

9,  These  effects  do  not  always  follow  the  use  of  alcohol, 
but  in  very  many  cases  they  do.     They  are  the  possibili- 
ties and  dangers  of  the  drug. 


QUESTIONS. 

SECTION  I.  —  1,  Why  do  we  need  food  ? 

2,  What  is  the  alimentary  canal  ? 

3,  4,  What  is  its  length  and  diameter  ? 

5,  What  important  tissue  in  its  wall  ? 

6,  What  is  mucous  membrane? 

7,  Give  the  divisions  of  the  alimentary  canal. 


DIGESTION  AND  ABSORPTION.  119 

9.  What  is  digestion  ? 

10.  Why  is  digestion  necessary  ? 

11.  Is  all  our  food  easily  dissolved? 

13, 14.  How  are  fats  digested  ?    What  is  an  emulsion  ?    What  are 
the  lacteals  ?    What  is  chyle  ? 

15,  What  has  the  muscle  of  the  alimentary  canal  to  do  with 
digestion  ?    Is  it  voluntary,  or  involuntary  ? 

16,  What  are  the  changes  that  constitute  digestion  ? 

17,  How  many  sets  of  teeth  do  we  have?    When  do  we  have  the 
largest  number  of  teeth  in  our  jaws  ? 

18,  Give  the  number  and  names  of  the  first  set. 

19,  Give  the  number  and  names  of  the  second  set. 

20,  How  do  the  teeth  indicate  the  habits  of  the  animal  ? 

21,  What  is  the  structure  of  a  tooth  ? 

22,  What  is  the  work  of  the  teeth? 

23,  How  may  the  teeth  be  injured  ? 

24,  How  is  the  mouth  kept  moist? 

25,  Name  the  salivary  glands.    Give  their  location. 

26,  What  are  their  outlets  ? 

27,  What  is  the  use  of  saliva  ? 

28,  Where  is  the  stomach  situated? 

29,  Describe  the  glands  of  the  stomach.    How  is  the  gastric  juice 
mixed  with  the  food? 

30,  What  is  the  pylorus  ? 

31,  What  two  large  glands  are  connected  with  the  upper  end  of 
the  small  intestine? 

32,  Where  is  the  liver  situated?    What  three   things  does   it 
do? 

33,  What  is  jaundice?    What  does  the  bile  do? 

34,  Where  is  the  pancreas?    What  is  its  structure? 

35,  What  does  the  pancreatic  juice  do? 

36,  What  glands  are  there  in  the  walls  of  the  small  and  the  large 
intestine?     What  is  the  fluid  that  comes  from  them  called,  and 
what  is  its  use  ? 

37,  Give  the  divisions  of  the  alimentary  canal.    Enumerate  the 
digestive  glands  in  the  canal.     What  is   their  product?    Enume- 
rate the  digestive  glands   outside  of  the  canal.    What  is  their 
product? 


120  THE  HUMAN  BODY. 

SECTION  II. — 1,2,  How  is  digested  food  carried  through  the  body? 

3,  Follow  «a  mouthful  of  food  in  its  progress  through  the  alimen- 
tary canal. 

4,  What  special  apparatus  for  absorption  in  the  small  intestine  ? 

5,  6,  7,  Describe  its  action. 
9,  Is  water  digested  ? 

SECTION  III. — 1.  What  is  the  lymphatic  system  ?    What  are  the 
names  of  the  tubes  in  which  the  lymphatic  vessels  terminate? 

2,  State  the  difference  between  the  lymphatic  system  and  the 
circulating  system. 

3,  What  is  the  use  of  the  lymphatics? 

4,  What  are  the  lacteals? 

SECTION  IV.  —  Name  some  hinderances  to  digestion. 

SECTION  V. — 1.  What  is  the  effect  of  alcohol  on  the  mucous 
membrane? 

2,  What  was  its  effect  on  the  stomach  of  St.  Martin  ? 

3,  How  does  the  stomach  adapt  itself  to  alcohol? 

4,  What  effect  has  alcohol  on  the  gastric  juice? 

5,  What  effect  on  the  intestine? 

6,  How  does  alcohol  reach  the  liver?  and  how  does  it  sometimes 
affect  it? 

8,  What  is  the  effect  of  alcohol  on  the  kidneys? 


RESPIRATION  AND   THE    VOICE.  1*21 


CHAPTER   VIII. 
RESPIRATION    AND    THE    VOICE. 

SECTION  I.  —  Air.     1.    We  have  studied  the  processes  of 
digestion  and  absorption,  by  which  food  and  water  get  . 
into  the  blood,  to  be  distributed  through  the  body.     It 
remains  to  study  the  method  by  which  air  is  taken  in  and 
used.     The  process  is  called  respiration. 

2,  We  live  in  air,  and  we  can  not  live  out  of  it  any 
more  than  fishes  can  live  out  of  water.  We  can  not  see 
the  air,  but  we  can  feel  it.  When  it  is  moving  very 
rapidly,  it  has  great  force.  It  can  root  up  trees,  and 
carry  away  houses.  If  we  could  see  it,  it  would  appear 
like  water.  When  the  wind  is  blowing,  we  would  see  a  ( 
stream  of  it  pouring  across  the  country  like  a  river,  or 
like  a  flowing  sea. 

SUGGESTIONS  TO  TEACHERS. — SECTION  I.  A  few  chemical  experiments 
will  illustrate  this  section.  Show  the  effect  of  oxygen  and  of  carbonic-acid 
gas  on  a  burning  candle.  Fill  a  test-tube  with  lime-water,  and  breathe  into 
it  to  demonstrate  carbonic-acid  gas  by  the  formation  of  a  milky  precipitate 
of  carbonate  of  lime. 

SECTION  II.  Show,  if  possible,  a  fish's  gills.  Illustrate  by  drawings; 
by  a  bunch  of  grapes,  etc.  Get  a  piece  of  lung  from  the  butcher's,  or,  still 
better,  the  lungs  and  air-passages  of  some  small  animal. 

SECTION  III.  The  nasal  cavities  should  be  shown,  either  in  the  human 
skull,  or  in  that  of  a  sheep  or  other  animal. 

SECTION  IV.  Simple  experiments  with  the  apparatus  mentioned  in  the 
text,  will  illustrate  the  principles. 

SECTION  VI.     Show  the  moisture  in  the  breath  by  breathing  on  glass. 

SECTION  VII.  A  larynx  can  easily  be  got  from  a  butcher,  and  the  glottis 
and  vocal  cords  and  muscles  can  be  shown. 


122  77/2?  HUMAN  BODY. 

3,  Air  is  a  material  substance,  though  invisible.     It  is 
in  the  gaseous  condition.     It  is  composed  chiefly  of  three 
gases  mixed. 

COMPOSITION    OF   AIR. 

Nitrogen,  about 79  parts  in  a  hundred. 

Oxygen,  about       ....       21          «..««« 
Carbonic-acid  gas,  about  .        .  .04      "     "        " 

Besides,  there  is  watery  vapor,  and  a  little  of  various  other 
substances. 

4,  Nitrogen  gas,  which  constitutes  nearly  four-fifths  of 
the  air,  is  not  used  either  by  animals  or  plants.     Neither 
is  it  injurious.     Its  office  is  to  dilute  the  oxygen.     If  we 
put  a  lighted  candle  into  a  jar  containing  pure  oxygen,  it 
will  burn  up  very  rapidly.     So,  if  an  animal  is  made  to 
breathe  pure  oxygen,  it  is  greatly  excited;  and  its  life, 
which  is  partly  a  burning,  is  quickly  burned  out.     The 
nitrogen  in  the  air  dilutes  the  oxygen  to  just  the  right 
strength. 

5,  Carbonic-acid  gas  is  not  used  by  animals.     On  the 
other  hand,  they  are  constantly  throwing  it  off  as  a  waste 
product.     But  plants  live  on  it:  it  is  a  large  part  of  their 
food.     As  they  take  it  in,  they  give  off  oxygen. 

Animals  take  in  oxygen,  and  give  out  carbonic-acid  gas. 

Plants  take  in  carbonic-acid  gas,  and  give  out  oxygen. 

Fires,  and  the  decay  of  animal  and  vegetable  matters,  are 
adding  constantly  to  the  carbonic-acid  gas.  But  there  is 
only  one  process  which  is  adding  to  the  oxygen  ;  and  that 
is,  the  action  of  the  leaves  of  plants.  On  the  whole,  the 
addition  and  subtraction  are  equal.  The  amount  of  car- 
bonic-acid gas  in  the  whole  air  remains  the  same,  though 
in  a  smoky  city  it  is  greater  than  it  is  in  the  country. 


RESPIRATION  AND   THE   VOICE.  123 

Fires  1 

Decaying  matters  L add  to  the  carbonic-odd  gas. 

Living  animals 

Living  plants  add  to  the  oxygen. 

6,  Oxygen  is  the  most  remarkable  of  the  elements. 
Three-fourths  of  the  material  of  which  our  bodies  are 
made  is  oxygen:  eight-ninths  of  the  material  of  which 
water  is  made  is  oxygen.  It  is  more  than  half  the  weight 
of  many  other  substances.  We  can  not  live  five  minutes 
without  a  fresh  supply  of  it.  It  is  infinitely  more  valu- 
able than  gold,  but  is  free  to  all.  We  do  not  have  to 
work  for  it,  as  we  do  for  food:  we  take  it  from  the  air  we 
breathe. 

THE    LUNGS. 

SECTION  II. — 1.  The  whole  of  the  air  that  we  take  in 
does  not  enter  the  blood.  Just  as  the  digestible  rtarts  of 
our  food  are  absorbed,  while  the  indigestible  parts  are 
cast  out,  so  that  part  of  the  air  that  we  need,  which  is 
oxygen,  is  absorbed  in  the  lungs,  and  the  rest  is  breathed 
out. 

2.  The  lungs  are  masses  of  little  cells,  with  very  thin 
walls,  placed  in  the  chest.     On  the  outside  of  the  walls  of 
these  sacs  are  the  capillaries,  —  millions  of  them.     They 
cover  the  sacs  as  the  netting  covers  a  balloon,  only  they 
are  much  closer  than  such  a  net.     The  blood  from  the 
pulmonary  artery   pours   into   these   capillaries,  and  so 
spreads  out  all  over  the  lung-cells.     The  oxygen,  then,  has 
only  to  pass  through  the  thin  lung-cell  and  the  thin  capil- 
lary wall  to  enter  the  blood. 

3.  Frogs  get  a  part  of  their  oxygen  through  their  skins. 
These  are  delicate  and  -  moist,  and  just  beneath  them  the 
net-work   of    capillaries    is    spread   out.     Oxygen   easily 


124 


THE  HUMAN  BODY. 


passes  through.  As  there  is  considerable  air  dissolved  in 
the  water,  they  can  live  under  it  all  winter  on  what  oxy- 
gen they  can  take  in  from  it  through  their  skins.  Man's 


Lung. 


Lung. 


Pericardium. 


Fig.  47. 
LUNGS  IN  POSITION,  THE  WALL  OF  TUE  CHEST  BEING  CUT  AWAY. 

skin  is  thicker,  and  does  not  allow  the  oxygen  to  pass 
through. 

4,  Fishes  have  a  peculiar  way  of  getting  their  oxygen. 
They,  of  course,  must  take  it  from  the  air  which  is  dis- 
solved in  the  water.  On  each  side  of  their  throats  they 


RESPIRATION  AND    THE   VOICE.  125 

have  an  opening,  in  which  are  a  number  of  flat  plates 
of  membranes,  called  gills,  with  net-works  of  blood-ves- 
sels in  them.     The  water  is  swallowed,  and 
passes  out  between  the  plates  through  these 
openings.     The  oxygen  which  it  contains 
enters   through  the   thin  membranes   into 
the  vessels. 

5.  Other  animals   take  in  oxygen   in   a 
different  way.     But,  though  the  way  is  dif- 
ferent, the  principle  is  the  same.     In  every  GlLLf f;      EBL> 
case,  the  capillary  vessels  are  spread  over 

a  thin  membrane;   and  the  air  is  on  the  other  side  of 
that  membrane. 

6,  In  some  of  the  lower  animals,  the  lung  is  a  single 
sac,  like  a  bladder,  with  the  capillaries  on  the  outside. 
In  man,  instead  of  being  a  single  sac,  each  lung  is  a  vast 
number  of  very  small  sacs  bound  together  in  a  mass,  with 
fine  blood-vessels  and  air-tubes  surrounding  and  connect- 
ing them. 

Imagine  a  bunch  of  grapes  with  the  contents  of  each 
grape  taken  out,  leaving  only  the  skins  to  represent  the 
air-cells.  Suppose  the  stems  to  be  hollow,  and  they  will 
represent  the  air-tubes.  Now,  put  several  such  bunches 
together,  so  that  the  main  stems  all  join  in  one  large 
stem,  and  you  have  something  which  represents  the  air- 
cells  and  air-tubes  of  a  lung.  To  make  it  complete,  sup- 
pose all  the  grapes  to  be  joined  by  fine  threads,  like  a 
spider's  web.  This  represents  the  fibrous  tissue,  which  is 
quite  elastic.  Suppose  a  blue  tube  to  run  along  the  main 
stem,  and  divide  every  time  the  stem  does,  until  its  small 
branches  finally  reach  every  grape,  and  form  a  net-work 
on  it.  From  that  net-work  suppose  red  tubes  to  run 


126 


THE  HUMAN  BODY 


back  by  the  sides  of  the  blue  ones,  joining,  constantly, 
other  tubes,  until  all  are  united  in  two  large  ones  on  the 
main  stem  of  our  bunches  of  grapes.  The  blue  tubes  are 
the  pulmonary  artery  and  its  branches.  The  net-works 
on  the  grapes  are  the  capillaries,  and  the  red  tubes  are 
the  pulmonary  veins. 


Bronchial 
tubes. 


Larynx. 


Fig.  49. 
SECTION  OF  THE  LUNGS,  PARTLY  SHOWING  THE  COURSE  OF  THE  BRONCHIAL  TUBES. 

Ill  such  a  figure  we  have  the  air-tubes  and  air-cells:  we 
have  the  blood-vessels,  and  we  have  the  fibrous  tissue.  If 
we  add  the  lymphatic  vessels  and  nerves,  we  have  all  that 
makes  up  the  lung. 


RESPIRATION  AND    THE    VOICE.  127 

7,  A  tree  is  another  illustration  of  a  lung.     The  trunk 
represents  the  bronchus,  or  great  air-tube,  which  enters 
the  lung.     The  branches  represent  the  small  (bronchial) 
tubes.     The  leaves  represent  the  air-cells.     If  we  suppose 
tubes  to  be  laid  along  the  trunk  and  branches,  constantly 
dividing,  until  finally  each  leaf   is  covered  with  a  net- 
work from   which  other  tubes  come  off,  and    run   back 
toward  the  trunk,  uniting  as  they  go,  we  shall   have 
again  something  like   a  lung,  with   the   fibrous  tissue, 
the  nerves,  and  lymphatic  vessels  and  glands,  still  to  be 
added. 

8,  Do  not  suppose,  however,  that,  on  examining  a  lung, 
you  would  see  all  these  tubes  and  cells.     On  the  contrary, 
you  would   see  only  a   light-gray  or  pinkish  substance, 
mottled  with  black  spots,  very  smooth  on  the  outside.     If 
you  were  to  cut  into  it,  it  would   look  a  little  like  fat. 
The  cells,  and  many  of  the  tubes,  are  so  small,  that  only 
very  careful  study  with  the  microscope  has  given  us  our 
knowledge  of  them. 

THE    AIR-PASSAGES. 

SECTION  III. — 1,  The  passages  by  which  the  air  gets 
to  the  lungs,  are, — 

The  nose,  The  larynx,     ) 

The  mouth,  The  trachea,  j  (*WH*P»I*)- 

The  throat,  The  bronchi. 

2,  The  nose  is  the  true  breathing  passage.  It  consists 
of  two  parts:  — 

i.  The  triangular  projection  from  the  face.  This  is 
partly  cartilage,  which  is  flexible,  and  partly  bone. 

$.  The  cavities  behind,  called  the  nasal  fossse.  There 
are  two  of  these,  corresponding  to  the  two  nostrils,  sepa- 


128 


THE  HUMAN  BODY. 


Fig.  50. 

SECTION  OF  NASAL  FOSSAE,  SEEN  FROM 
BEHIND. 


rated  by  a  partition.  They  are  narrow,  but  quite  exten- 
sive. They  enter  into  the  upper  part  of  the  throat  by 
two  openings,  like  the  two  on  the  face.  Above,  they  con- 
nect with  cavities  in  the 
forehead,  and  at  the  sides 
with  cavities  in  the  upper 
jaw-bones,  and  with  the 
eye.  These  passages  and 
cavities  are  lined  with 
mucous  membrane;  and 
when  this  is  inflamed,  as 
in  a  cold  in  the  head,  we 
have  a  feeling  of  fullness, 
not  only  in  the  nose,  but 
also  in  the  forehead  and 
eyes. 

3,  The  nerves  of  smell  are  up  in  the  top  of  the  nasal 
cavities.     In  ordinary  breathing,  the  air  passes  straight 
back   to   the  throat;    but,  when  we   wish   to  smell  any 
thing  distinctly,  we  sniff  suddenly,  and  so  draw  the  air 
up  to  the  top  of  the  cavities,  with  the  odorous  particles 
in  it. 

4,  The  odorous  particles  will  diffuse  themselves  through 
the  cavities,  and  reach  the  nerves,  without  this  sniffing, 
unless  they  are  few  and  faint.     But,  by  sniffing  the  air, 
we  get  the  sensation  more  quickly  and  keenly. 

5,  A  horse  can  not  breathe  through  his  mouth,  but  a 
man  can.     We  do  so  when  the  nose  is  stopped,  and  when 
we  are  breathing  rapidly,  as  in  exercise.     Some  always 
do  so  when  asleep. 

It  is  better  to  breathe  through  the  nose,  because,  — 
1.  The  nasal  cavities  being  narrow,  the  air  is  spread  out 


HEHPIUATION  AND    THE   VOICE.  129 

in  a  thin  sheet,  and  so  is  warmed  by  the  warm  walls  of 
the  cavities.  It  passes  through  the  mouth  in  a  large 
stream,  and  pours  into  the  lungs  without  being  properly 
warmed  in  cold  weather. 

2.  Dry  air,  passing  through  the  nasal  cavities,  is  not  only 
warmed,  but  moistened.     When  it  is  taken  through  the 
mouth,  it  dries  the  throat,  as  any  one  can  learn  by  trying 
it  rapidly  for  a  few  moments.     Hence,  the  practice  tends 
to  produce  sore-throat. 

3.  Snoring  is  a  result  of  sleeping  with  the  mouth  open. 
The  soft  palate,  which  hangs  like  a  curtain  between  the 
passages  from  the  nose  and  the  mouth,  is  relaxed  in  sleep. 
The  two  currents  of  air,  one  on  each  side  of  it,  cause  it  to 
vibrate  rapidly,  just  as  a  sheet  will  flap  and  rattle  in  the 
wind. 

6,  The  habit  of  breathing  through  the  nose,  both  in 
waking  and  sleeping   hours,  should,  therefore,  be  culti- 
vated.   One  of  the  best  safeguards  against  catching  cold  in 
the  throat,  on  going  from  a  heated  room  into  the  night 
air,  is  to  keep  the  mouth  shut. 

7,  The  throat  is  both  a  food-passage  and  an  air-passage. 
Air  is  sometimes  swallowed  into   the  stomach :  food  and 
drink  sometimes  enter  the  wind-pipe ;  but,  if  they  do,  there 
is  a  great  disturbance,  and  they  must  be  coughed  out  at 
once.    Commonly,  each  takes  its  proper  course, — the  food 
through  the  gullet,  the  air  through  the  wind-pipe,  and  that 
without  any  thought  on  our  part.     The  apparatus  is  self- 
regulating.     When    we   swallow,    the   breathing-passage 
closes  up  tight;  and  a  kind  of  trap-door,  called  the  epi- 
glottis, shuts  down   over  it.      You  can  not  swallow  and 
breathe  at  the  same  time. 

8,  The  larynx,  which  is  the  upper  part  of  the  wind- 


130  THE  HUMAN  BODY. 

pipe,  is  a  kind  of  a  box  made  of  cartilage.  It  is  wider 
than  the  rest  of  the  wind-pipe,  and  projects  in  front, 
making  Adam's  apple.  It  is  the  voice-box.  In  it  are 
the  vocal  cords,  or  bands,  by  which  sound  is  made.  It 
will  be  more  fully  described  hereafter. 

9,  The  trachea  is  a  tube  four  or  five  inches  long,  and 
from  half  an  inch  to  an  inch  in  diameter,  extending  from 
the  larynx  down  into  the  chest.     It  is  made  of  a  series  of 
flat  rings  of  cartilage,  sixteen  or  twenty  in  number,  which 
do  not  quite  come  together  behind,  but  are  somewhat  like 
a  horseshoe.    These  are  connected,  and  covered  with  mem- 
brane and  muscular  fibers.     They  serve  to  keep  the  tube 
open. 

10,  The  trachea  divides  into  two  branches,  called  bron- 
chi.     One  goes  to  the  right,  and  one  to  the  left,  lung. 
They  are  made  just  like  the  trachea,  and  are  one  or  two 
inches  long. 

11,  Each  bronchus,  as  it  enters  the  lung,  divides  into 
smaller  tubes,  called  bronchial  tubes;  and  these  keep  on 
dividing  until  they  are  not  more  than  TJ-^  of  an  inch  in 
diameter.     They  then  end  in  the  air-cells. 

BREATHING. 

SECTION  IV. —  1.  We  have  studied  the  lungs,  and  the 
passages  leading  to  them.  We  have  now  to  study  the 
process  by  which  air  goes  in  and  out  of  them.  It  is  not 
enough  that  the  passage  is  open.  The  lungs  are  not  like 
a  house,  with  windows  and  doors,  through  which  the 
breeze  plays  freely.  They  are,  rather,  like  a  deep  well, 
or  a  mine,  into  which  fresh  air  will  not  go,  unless,  in 
some  way,  a  current  is  made.  We  make  this  current  by 
breathing. 


It  EXPIRATION  AND    THE    VOICE. 


131 


2.  If  you  watch  the  breathing,  you  will  see  two  regular 
movements.     First,  the  chest  and  abdomen  seem  to  swell ; 
and  then,  in  a  moment,  they  fall  back  to  their  former 
size.     This  is  repeated  with  every  breath.     The  chest  does 
enlarge;  and,  as  it  enlarges,  the  air  rushes  in,  to  fill  the 
extra  space.     As  it  grows  smaller,  the  same  amount  of  air 
that  entered  is  squeezed  out  again. 

Why  does  the  air  rush  in,  when  the  spa.ce  is  made 
larger?  Because  air  is  like 
water :  it  is  pressing  in  every 
direction.  If  you  put  water 
in  a  tub  with  a  pipe  opening 
out  of  it,  it  will  force  itself 
into  the  pipe.  If  you  put 
a  bottle  under  water,  wdth 
the  mouth  up,  the  water  will 
push  in,  and  fill  it.  We  are 
in  the  air  as  the  bottle  is  in 
the  water.  If  the  bottle  is 
made  of  rubber,  the  water  will 
flow  out  when  we  squeeze  it, 
and  will  flow  in  again  when 
it  expands.  The  chest  may 
be  likened  to  such  a  rubber 
bottle. 

The  chest  is  like  a  bellows,  with  one  exception :  in  a 
bellows,  the  air  enters  by  one  opening,  and  goes  out  of 
another ;  in  the  chest,  air  enters  and  goes  out  by  the  same 
opening. 

3.  How  is  the  chest  made  larger  ?     In  two  ways, — 
l.  By  the  descent  oil  the  diaphragm. 

s.  By  the  raising  of  the  ribs  and  breast-bone. 


Fig.  51. 
THE  CHEST. 


132  77/1?  HUMAN  BODY. 

The  diaphragm  is  attached  to  the  lower  edge  of  the 
walls  of  the  chest,  and  stretches  across,  separating  chest 
from  abdomen,  forming  the  floor  of  one  and  the  roof  of 
the  other.  But  it  is  not  a  flat  floor.  It  arches  up  into  the 
chest,  as  may  he  seen  in  the  figure,  and  is  supported  in 
this  position  by  the  contents  of  the  abdomen  beneath  it. 
When  we  take  a  breath,  the  diaphragm  contracts, — 
being  partly  muscle,  —  and  the  top  of  the  arch  is  flattened, 
making  more  room  in  the  chest.  At  the  same  time,  the 
contents  of  the  abdomen  are  pressed  down,  and  the  walls 
of  that  cavity  expand  to  accommodate  them.  The  ab- 
domen is  not  made  larger  when  we  take  breath.  It  ex- 
pands in  front  just  enough  to  make  up  for  what  it  loses 
by  the  flattening  of  its  roof. 

4,  But  the  chest  is  enlarged,  not  only  by  the  descent  of 
its  floor,  but  also  by  the  raising  of  the  ribs  and  breast- 
bone.    The  ribs  are  joined  to  the  backbone  behind,  and 
connected  with  the  breast-bone  by  the  costal  cartilages, 
which  will  bend.     To  the  ribs  are  attached  muscles  which 
pull  them  up,  and  others  which  pull  them  down.     The 
former  are  called  inspiratory  muscles,  and  the  latter  expir- 
atory muscles.     Now,  clasp  your  hands,  and  extend  your 
arms  in  front  of  you,  slanting  a  little  downward.     Your 
hands  represent  a  portion  of  the  breast-bone,  and  your 
arms  two  of  the  ribs.     Keeping  your  hands  clasped,  raise 
your  elbows  as  much  as  you  can,  and  raise  your  hands  a 
little.     That  is  the  motion  that  the  inspiratory  muscles 
give  to  the  ribs  and  breast-bone.     You  can  see  that  the 
space  included  between  them  is  enlarged  in  both  direc- 
tions. 

5,  We  have  been  speaking  of  the  cavity  of  the  chest. 
The  air  enters  the  lungs.     But  the  lungs  occupy  almost 


RESPIRATION  AND   THE   VOICE.  133 

all  of  the  chest,  except  the  space  filled  by  the  heart. 
They  are  attached  to  its  walls  and  floor.  They  are  elas- 
tic; and  so,  when  the  chest  enlarges,  the  lungs  enlarge 
with  it,  and  the  air-cells  open  wride.  When  the  chest 
sinks  back  to  its  former  size,  the  elastic  lung  shrinks  too ; 
and  the  air  is  driven  out. 

6.  The  lungs  are  held  to  the  chest-wall  by  the  pleurae. 
These  are  two  empty,  air-tight  sacs,  one  for  each  lung. 
One  layer  covers  the  lung;  and  the  other  lines  the  chest- 
wall,  and   is  attached   to  it.     The   insides  of  these  two 
sacs  are  moistened  by  a  fluid,  so  that  there  is  no  friction 
between  the  lung  and  the  chest :  and,  as  the  sacs  are  air- 
tight, the  layers  can  not  be  separated ;  and  the  chest- wall, 
in  its  movements,  pulls  the  lung  with  it,  just  as  the  circle 
of  wet  leather,  which  the  boys  call  a  sucker,  lifts  a  stone. 
The  pleura  is  like  the  inner  portion  of  the  pericardium. 

7.  To  recapitulate  briefly.    The  lungs,  consisting  largely 
of  little  air-cells,  with  the  air-tubes  leading  to  them,  are 
elastic.     They  nearly  fill  the  chest,  and  cling  closely  to 
its  walls  and  floor.     When  the  chest  expands  by  the  de- 
scent of  its  floor  and  the  ascent  of  its  walls,  the  lungs 
expand  with  it.     The  air-cells  open,  and  the  outside  air  is 
pushed  in  to  fill  them, — as  the  air  enters  a  bellows  when 
we  separate  its  walls.     When  the  inspiratory  muscles  stop 
pulling,  the  chest  settles  back  to  its  former  size,  the  expi- 
ratory muscles  helping  it  a  little,  and  sometimes  a  good 
deal. 

8.  We  breathe  without  thinking  of  it  in  sleep  as  well 
as  when  awake.     We  can  not  refrain  from  it  for  many 
seconds.     Constant  breathing   is   necessary  to  life,  so   it 
must  be  independent  of  our  wills. 


134  THE  HUMAN  VODY. 


CHANGES    IN   THE   BLOOD. 

SECTION  V. — 1.  Part  of  the  oxygen  of  each  breath 
taken  in,  after  reaching  the  air-cells,  goes  through  their 
walls,  and  through  the  walls  of  the  capillaries  outside  of 
them,  into  the  blood.  It  joins  itself  to  the  red  corpuscles ; 
and  they  float  on  with  it  through  the  heart,  and  out  into 
the  aorta,  and  finally  into  the  capillaries  of  all  parts  of  the 
body:  there  it  leaves  the  corpuscles,  drawn  by  a  more 
powerful  attraction  through  the  capillary  walls,  to  help 
to  nourish  and  build  up  the  surrounding  substance. 

2.  The  blood,  as  it  discharges  its  load  of  oxygen  from 
the  capillaries,  takes  up,  at  the  same  place,  a  new  load 
of  carbonic-acid  gas.     The  oxygen  is  the  nourishment  for 
the  tissues, — the  fuel  for  the  fire;  and  the  carbonic-acid 
gas  is  like  the  ash,  which  must  be  removed,  or  else  the  fire 
will  be  clogged.     As  the  blood  thus  changes  its  load,  a 
marked  change  in  its  color  takes  place.     As  it  conies  from 
the  lungs,  it  is  scarlet,  and  so  continues  through  the  heart 
and  arteries  until  it  reaches  the  capillaries:  there  it  turns 
blue,  and  so  continues  through  the  veins  and  the  heart 
and   the   pulmonary   artery  until   it   reaches   the   lungs 
again. 

In  the  capillaries  of  the  larger,  or  systemic,  circulation, 
the  blood  turns  blue. 

In  the  capillaries  of  the  lesser,  or  pulmonary,  circulation, 
the  blood  turns  scarlet. 

3,  We  know  that  it  is  the  oxygen  taken  in  by  the  lungs 
that  gives  blood  its  scarlet  color,  and  that  it  is  the  loss  of 
oxygen  in  the  tissues  that  makes  it  turn  blue.     For  if  we 
take  some  blue  blood  from  a  vein,  and  shake  it  up  in  the 
air,  it  will  turn  scarlet;  and  the  color  will  be  the  same 


RESPIRATION  AND   THE   VOICE.  135 

when  it  contains  much  carbonic-acid  gas  as  when  it  con- 
tains little. 

4,  The  blood  is  the  common  carrier  of  the  nutriment 
that  we  get  from  food  and  air ;  and  it  takes  away,  not  only 
carbonic-acid  gas,  but  all  other  waste  matters.  Some  it 
discharges  by  the  kidneys,  some  by  the  skin;  the  car- 
bonic-acid gas,  chiefly  by  the  lungs. 

WASTE  MATTERS   GIVEN   OFF  BY   THE   LUNGS. -CHANGES 
IN    THE   AIR. -VENTILATION. 

SECTION  VI. — 1,  The  lungs,  therefore,  serve  not  only 
to  take  in  oxygen,  but  also  to  discharge  carbonic-acid  gas, 
which  is  one  of  the  chief  waste  products  of  the  body. 

Another  product  of  the  waste  of  the  body,  which  is  dis- 
charged by  the  lungs,  is  water.  This  ordinarily  passes 
off  in  the  breath  as  invisible  vapor.  But  in  very  cold 
weather  it  is  condensed  as  it  comes  out,  and  we  can  see 
it.  It  lodges  and  freezes  on  the  beards  of  men,  and  on 
the  hair  of  animals.  If  the  vapor  in  the  breath  of  a  man 
is  collected  for  twenty-four  hours,  and  condensed  to  water, 
it  measures  as  much  as  a  pint. 

2,  The  breath  of  man,  and  of  every  animal,  when 
breathed  out,  contains,  besides  carbonic-acid  gas  and 
water,  a  very  little  of  a  certain  substance  which  gives  to 
each  its  peculiar  odor.  The  breath  of  a  cow,  for  ex- 
ample, has  a  smell  peculiar  to  the  animal.  In  pure, 
fresh  human  breath,  we  do  not  recognize  any  odor;  but 
the'  substance  is  present:  and  in  ill-ventilated  rooms, 
where  many  people  have  been  breathing,  it  becomes 
changed,  and  makes  the  air  offensive  and  unhealthy. 
These  three  substances  —  oxygen,  carbonic-acid  gas,  and 
an  unnamed  animal  substance  —  are  always  present  in 


136  THE  HUMAN  BODY. 

the   breath.     Other  matters  which   give  a  distinct  smell 
are  often  found  in  it,  but  not  constantly. 

3,  The  amount  of  air  in  a  single  breath  is  about  twenty 
cubic  inches,  which  would  be  a  globe  of  air  a  little  smaller 
than  a  base-ball.     We  take  .about  eighteen  breaths  in  a 
minute;  in  an  hour,  we  breathe  about  twelve  cubic  feet  of 
air;  and  in  a  day,  about  three  hundred.     Since  we  breathe 
more  than  eighteen  times  in  a  minute  when  we  are  exer- 
cising  actively,  probably   three   hundred   and   fifty   feet 
would  be  nearer  the  amount  used  in  a  day.     This  would 
equal  the  entire  contents  of  a  room  between  seven  and 
eight  feet  on  every  side. 

4,  Every  breath,  as  it  comes  from  the  mouth,  is  changed 
in  four  ways, — 

1.  It  has  lost  oxygen. 

&  It  has  gained  carbonic-acid  gas. 

s.  It  has  gained  watery  vapor. 

4-  It  has  gained  a  nameless  animal  substance. 

This  breath  is  not  fit  to  be  breathed  again.  To  be  sure, 
there  is  still  oxygen  in  it,  but  not  so  much  as  in  fresh  air. 
The  loss  of  even  one  of  the  twenty-one  parts  in  a  hundred 
of  oxygen,  which  fresh  air  contains,  makes  air  less  sup- 
porting; and  if  eleven  parts  are  lost,  though  there  are  still 
ten  parts  left,  we  could  not  live  in  it.  Moreover,  the 
carbonic-acid  gas  has  an  injurious  effect. 

5,  The  stream  of  air  which  we  pour  out  at  each  breath 
does  not  remain  distinct,  but  mixes  immediately  with  the 
surrounding  air,  just  as  a  glass  of  colored  fluid,  if  poured 
into  a  pail  of  water,  will  quickly  diffuse  itself  through  the 
whole.     We  never  breathe  precisely  the  same  breath  a 
second  time,  and  the  air  of  a  room  only  very  gradually 
becomes  bad  when  many  people  are  breathing  in  it.     In 


RESPIRATION   AND    THE   VOICE.  137 

a  large  room,  such  as  a  church,  many  people  can  remain 
for  a  long  time  without  suffering,  even  if  the  air  is  not 
changed.  They  may  not  be  aware  that  it  is  growing  im- 
pure, though  one  coming  in  from  out  of  doors  would  know 
it  at  once.  If  the  room  is  small,  the  air  must  be  constantly 
changed,  or  they  will  be  distressed. 

6,  The  Black  Hole,  at  Calcutta,  was  a  room  in  which 
one  hundred  and  forty -six  men  were  confined  over  night. 
It  was  eighteen  feet  square,  and  had  two  small  windows, 
through  which  the  air  did  not  come  freely.     Their  suffer- 
ings were  intense,  arid  only  twenty-three  of  them  were 
alive  in  the  morning. 

7,  Nothing  is  so  free  and  abundant  as  fresh  air;  and  yet 
we  all  suffer  frequently,  and  many  suffer  constantly,  for 
want  of  it.     We  should  always  remember  its  importance. 
It  is  possible  to  become  accustomed  to  close  rooms.     We 
may  not  know  what  is  the  cause  of  a  drowsy  head,  a  disin- 
clination to  exercise,  and  general  ill  health,  while  it  is 
simply  lack  of  fresh  air.     Sleeping-rooms,  in  which  we 
spend  a  third  of  every  day,  unconscious  of  the  state  of 
the  air,  should  be  well  ventilated. 

8,  It  is  very  difficult  to  get  fresh  air  enough  into  our 
dwellings  and  public  buildings,  and,  at  the  same  time,  to 
avoid  draughts,  and  keep  warm.     Ventilation  is  almost  a 
science  by  itself.     There  are  many  ways,  but  no  one  way 
which  will  do  for  every  room.    But  if  we  all  bear  in  mind 
the   necessity  of  fresh  air,  and   use   our  judgment   and 
ingenuity,  we  shall  get  it. 

THE  VOICE. 

SECTION  VII.  —  1,    The  organs  of  breathing  are,  at  the 
same  time,  organs  of  voice.     The  larynx  is  especially  the 


138 


THE  HUMAN  BODY. 


voice-box  ;  but  the  lungs,  the  bronchial  tubes,  the  trachea, 
and  the  throat,  mouth,  and  nose,  all  have  a  part  in  mak- 
ing and  forming  sounds. 

2,  The   toy  pipes,  which  have,  near  the  mouth-piece, 
narrow  bands  of  brass,  between  which  the  air  passes,  and 

which  make  a  reedy  sound,  are  some- 
what like  the  organ  of  voice.  The 
chest  and  lungs  give  the  wind,  the 
trachea  is  the  pipe,  the  larynx  contains 
the  vocal  cords,  which  make  the  sound. 
The  larynx  is  divided  in  two  parts  by 
a  membranous  partition,  which  has  a 
slit  in  it,  running  forward  and  back- 
ward. This  slit  may  be  opened  or 
shut,  or  made  longer  or  shorter,  by  the 
action  of  many  little  muscles,  which 
surround  it. 

The  edges  of  this  slit,  which  is  called 
the  glottis,  are  the  vocal  cords.  Every 
breath  has  to  Pass  through  it;  but, 
in  ordinary  breathing,  no  sound  is 
produced.  If  we  wish  to  make  a  sound,  the  little  mus- 
cles tighten  up  the  cords,  and  make  the  slit  narrow  ;  and, 
as  the  lungs  are  squeezed  in  the  chest,  the  air  forced  out 
through  the  slit  makes  the  cords  vibrate.  This  makes 
the  sound.  We  shape  this  sound  by  changes  in  our 
throats  and  mouths. 

3,  A  reed-organ  is  somewhat  like  the  vocal  apparatus  ; 
but,  in  the  instrument,  there  is  a  pipe  for  every  note.     The 
windpipe  can  be  so  varied  in  length  and  in  size,  and  the 
voice-box,  with  its  cords,  can  be  so  changed  in  many  ways, 
that  a  single  pipe  can  make  many  different  sounds. 


Fig.  52. 


RESPIRATION    AND    THE    VOICE.  139 

4.  The  voice  can  be  improved  by  cultivation.  The 
breathing-muscles  grow  stronger,  and  also  the  muscles  of 
the  voice-box  itself.  The  power  to  make  firm,  clear,  sweet 
sounds  increases.  It  is  by  singing  that  this  is  sought. 
But  singing  is  not  the  only  way  of  improving  the  vocal 
powers.  To  speak  well  is  of  more  consequence  than  to 
sing  well.  In  singing,  the  sound  is  the  main  thing,  and 
less  attention  is  paid  to  articulation.  In  speaking,  it  is 
important,  not  only  that  the  tones  should  be  clear  and 
pleasing,  but  also  that  the  pronunciation  of  words  and 
syllables  and  letters  should  be  distinct  and  correct.  By 
taking  care  in  speaking,  we  gradually  train  the  muscles 
of  the  tongue  and  cheeks  and  throat,  by  which  we  make 
words,  until  it  becomes  a  habit  to  speak  well. 

EFFECTS    OF    ALCOHOL    AND    TOBACCO. 

SECTION  VIII.  —  1.  If  more  than  a  small  amount  of 
alcohol  is  taken,  it  is  cast  out  of  the  body  unchanged. 
One  way  in  which  it  goes  out  is  by  the  breath.  The 
breath  of  an  habitual  drinker  always  betrays  him.  It 
contains,  besides  the  vapor  of  water  and  carbonic-acid  gas, 
which  are  natural,  the  vapor  of  alcohol,  which  is  unnat- 
ural. This  is  easily  known  by  its  odor,  and  is  offensive. 

2.  Tobacco  has  a  similar  influence  on  the  breath.     Its 
continuous  use,  even  in  moderate  quantity,  gives  an  odor 
to  the  breath  which  is  peculiar  and  disagreeable.     While 
fresh  tobacco-smoke  is  not  offensive  to  some  who  do  not 
use  it,  the  stale  fumes  which  cling  to  the  persons  and  the 
rooms  of  smokers  are  always  unpleasant. 

3,  The  bad  effects  of  tobacco-smoke  are  increased  when 
it  is  drawn  with  the  breath  into  the  lungs.     More  of  its 
poisonous  ingredients  pass  through  the  air-cells,  and  reach 
the  blood. 


140  THE    HUMAN   HODY. 

QUESTIONS. 

SECTION  I.  —  1.  What  is  respiration  ? 

2,  What  would  air  look  like  if  we  could  see  it? 

3,  Is  air  a  material  substance?    What  is  it  composed  of? 
4  What  is  the  use  of  the  nitrogen  in  the  air  ? 

5,  What  is  the  use  of  carbonic-acid  gas  in  the  air?    Does  man 
use  it  ?    What  is  adding  constantly  to  the  carbonic-acid  gas  in  the 
air?    What  is  adding  constantly  to  the  oxygen  in  the  air? 

6,  Name  some  characteristics  of  oxygen. 

SECTION  II.  —  1.  Does  all  of  the  air  which  we  breathe  in  enter 
the  blood? 

2,  What  are  the  lungs?     How  does  the  oxygen  pass  through 
them  into  the  blood-vessels? 

3,  How  do  frogs  breathe  under  water? 

4,  How  do  fishes  breathe? 

5,  In  what  are  all  breathing-organs  alike  ? 

6,  Illustrate  the  structure  of  a  human  lung  by  a  bunch  of  grapes. 

7,  Illustrate  the  structure  of  a  lung  by  a  tree. 

8,  Can  this  structure  be  seen  with  the  naked  eye? 

SECTION  III. — 1.  Name  the  passages  by  which  the  air  reaches 
the  lungs. 

2.  What  two  parts  does  the  nose  consist  of?    With  what  other 
cavities  are  the  cavities  of  the  nose  connected? 

3,  4.  Where  are  the  nerves  of  smell,  and  how  do  the  odorous 
particles  reach  them? 

6.  Give  three  reasons  for  breathing  through  the  nose  rather  than 
the  mouth. 

6,  What  is  a  safeguard  against  taking  cold  when  going  from  a 
heated  room  into  cold  air? 

7.  Where  do  the  air-passage  and  the  food-passage  cross  each 
other?    Why  does  not  food  enter  the  windpipe? 

8.  What  is  the  larynx? 

9,  Describe  the  trachea. 

10,  Into  what  does  the  trachea  divide  ? 

11.  Describe  the  course  and  termination  of  the  bronchial  tubes. 

SECTION  IV.  —  1.  Does  air  enter  the  lungs  of  itself? 

2,  What  movements  can  we  see  when  we  watch  a  person  breath- 


RESPIRATION    AND    THE    VOICE.  141 

ing?    What  change  takes  place  in  the  chest?    Why  does  the  air 
enter  it  ?    WThat  is  the  chest  like  ? 

3,  In  what  two  ways  is  the  chest  made  larger  ?    Describe  the  first- 
named  way. 

4,  Describe  the  second-named  way. 

5,  Why  do  the  lungs  enlarge  when  the  chest  does? 

6,  What  are  the  pleurae? 

7,  Describe  briefly  the  process  of  breathing. 

8,  Does  the  will  have  any  thing  to  do  with  ordinary  breathing? 

SECTION  V. — 1.  Follow  the  course  of  oxygen  as  it  enters  the 
blood. 

2,  What  change  in  the  color  of  the  blood  takes  place?    Where 
does  the  change  from  red  to  blue  take  place?    Where  does  the 
change  from  blue  to  red  take  place? 

3,  What  is  the  cause  of  the  change  in  color? 

4,  What  is  the  work  of  the  blood? 

SECTION   VI.  — 1,  2,  What  do   the  lungs  do  besides  taking  in 
oxygen?    What  waste  products  are  discharged  by  the  lungs? 

3.  How  much  air  is  there  in  a  breath?    How  much  air  do  we 
breathe  in  a  day? 

4.  What  four  changes  take  place  in  every  breath?    Has  it  lost  all 
its  oxygen?    How  much  oxygen  must  air  contain  to  support  life? 
How  small  a  loss  of  oxygen  will  be  felt  ? 

5.  Do  we  breathe  the  same  air  a  second  time? 

7.  What  are  the  immediate  effects  of  lack  of  fresh  air? 

8,  How  should  we  try  to  secure  fresh  air  ? 

SECTION  VII.  — 1.  What  are  the  organs  of  voice? 

2,  How  are  the  organs  of  voice  like  a  reed-pipe?  and  what  part 
does  each  do?    What  is  the  glottis?    What  are  the  vocal  cords? 

3,  What  resemblance  between  the  vocal  organs  and  a  reed-organ? 

4,  How  should  the  voice  be  cultivated  ? 

SECTION  VIII.  —  1,  What  is  the  effect  of  alcohol  on  the  breath  ? 
2,  3,  What  is  the  effect  of  tobacco  on  the  breath  ? 


142 


THE  HUMAN  BODY. 


Cerebrum. 


Fig.  53. 
GENERAL  REPRESENTATION  OF  THE  NERVOUS  SYSTEM. 


THE  NERVOUS  SYSTEM.  143 


CHAPTER   IX. 
THE    NERVOUS    SYSTEM. 

SECTION  I.  —  1,  An  injury  to  the  head,  if  violent 
enough,  will  kill  at  once.  If  less  violent,  it  will  stun  the 
victim.  He  will  drop,  limp  and  helpless,  and  will  know 
nothing  for  a  time;  but  his  heart  will  continue  to  beat 
feebly,  and  he  will  still  breathe.  In  time  he  will  get  his 
senses,  and  his  power  over  his  muscles  again. 

2,  An  injury  to  the  backbone,  if  violent  enough,  will 
paralyze  the  lower  limbs.     The  man  is  not  stunned  ;  and 
he  breathes,  and  his  heart  beats.     He  can  move  with  all 
the  muscles  above  the  injury:  but  those  below  are  useless, 
though  they  have  not  been  hurt ;  and  perhaps  he  will  have 
no  feeling  in  those  parts.     In  the  case  of  the  injury  on 
the  head,  the  part  that  is  hurt  is  the  brain.     In  the  case 
of  the  injury  on  the  back,  the  part  that  is  hurt  is  the 
spinal  cord. 

3,  The  brain  fills  the  chief  cavity  of  the  skull.     It  is 
not  one  mass,  but  several  masses  joined  together.     The 
largest  mass  is  called  the  cerebrum.     The  next  in  size  is 
the  cerebellum  (little  brain),  which  lies  behind  and  beneath 
the  cerebrum.     The  pom  Varolii  is  a  mass  in  front  of  the 
cerebellum   and   beneath    the   cerebrum.      The    medulla 
oblongata  is  beneath  the  cerebellum,  and  behind  the  pons 
Varolii. 

SUGGESTION  TO  TEACHERS.  —  SECTION  I.  3.  Get  a  sheep's  or  calfs  brain. 
The  chief  divisions,  the  convolutions,  and  the  gray  and  white  matter,  can  be 
shown. 


144  THE  HUMAN  BODY. 

4,  Each  of  these  masses  is  in  two  halves,  which  are 
precisely  alike.    The  two  halves  of  the  cerebrum  and  cere- 
bellum are  partly  separate.     The  two  halves  of  the  pons 
and  the  medulla  are  united. 

5,  The  surface  of  the  cerebrum  and  cerebellum,  instead 
of  being  smooth,  is  divided  into  ridges,  with  furrows  be- 
tween them.     These  ridges  are  called  the  convolutions  of 


Fig.  54. 

HALF  OP  THE  BRAIN,  AND  UPPER  END  OF  THE  SPINAL  CORD,  WITH  THE  NERVES 
COMING  FROM  THEM.  — 1.  Cerebrum.  2.  Cerebellum.  3.  Pons  Varolii.  4.  Medulla 
oblongata.  5.  The  Eyeball. 

the  brain.  One  great  difference  between  the  brain  of  man 
and  of  the  lower  animals  is,  that  it  has  more  of  these 
convolutions.  Very  intelligent  animals  have  more  of 
them  than  animals  less  intelligent. 

6,  The  medulla  oblongata  is  the  lowest  portion  of  the 
brain.  It  is  just  above  the  great  opening  in  the  base  of 
the  skull.  Through  that  opening,  it  is  continuous  with 
the  spinal  cord. 


THE  NERVOUS   SYSTEM. 


145 


7,  The  spinal  cord  occupies  the  spinal  canal   in    the 
backbone.     It  is  about  half  an  inch  thick,  and  eighteen 
inches  long.     Before  reaching  the 

lower  end  of  the  canal,  it  divides  > 
into  a  bunch  of  fine  cords,  which  * 
make  the  cauda  equina  (horse's  » 
tail).  1 

The  spinal  cord,  like  the  brain,  £ 
is  partly  divided,  lengthwise,  into  gj 
two  halves,  which  are  alike.  » 

8,  Both   the   brain   and   spinal      § 
cord  have  three  coverings  wrapped      | 
around  them,  called  the  membranes      *    |»j 
of  the  brain  and  cord. 

From  each  half  of  the  brain  §  ^ 
twelve  small  cords  come  off,  and  j* 
go  out  through  holes  in  the  skull.  ~ 
From  each  half  of  the  spinal  cord  * 
thirty-one  small  cords  come  off,  » 
by  two  roots  each,  and  go  out  of  » 
the  spinal  canal  through  openings  § 
between  the  vertebrae.  These  are  I 
the  nerves. 

9,  The  substance  of  the  brain 
and  cord  is  soft  and    cheese-like,      g 
It  is  of  two  colors,  white  and  gray. 

The  whole  surface  of  the  cerebrum  and  cerebellum,  about 
a  quarter  of  an  inch  deep,  is  gray.  The  deep  parts  of  both 
are  chiefly  white.  In  the  cord,  it  is  different.  The  deep 
part  is  gray,  and  the  surface  is  white. 

10,  A  blow  on  that  part  of  the  elbow  called  the  "funny- 
bone,"  gives  a  tingling  sensation  all  the  way  down  to  the 
little  finger. 


146 


THE  HUMAN  JiODY. 


If  we  should  cut  into  the  elbow  to  find  the  "  funny- 
bone,"  we  would  come  upon  a  flat,  shining  cord  about  an 
eighth  of  an  inch  wide.  If  we  should  follow  this  cord 
down,  we  would  find  it  divide  into  smaller  cords;  and,  if 
we  should  follow  each  one  of  these,  we  would  see  it  finally 
ending  in  the  muscles,  or  in  the  skin,  or  some  other  tissue, 
in  a  great  many  fibers,  so  fine  that  only  a  microscope 
would  show  them.  Many  of  them  go  to  the  little  finger, 
where  the  tingling  is  most  felt.  If  we  should  search 
farther  for  such  cords,  we  would  find  that  they  were  in 
nearly  every  part.  We  would  find  that  some  of  them 
were  as  large  as  the  one  first  seen,  but  that  the  smallest 
were  smaller  than  the  capillary  blood-vessels,  and  as 
numerous. 

11,  If,  starting  from  the  elbow,  we  should  follow  the 
cord  first  found  up  the  arm,  we  would  see  it  joining  other 
cords,  and  perhaps  itself  dividing ;  and  finally  we  would 
trace  it  through  one  or  more  of  the  openings  between  the 

vertebra?  (intervertebral  fora- 
mina) into  the  spinal  cord. 

If  we  followed  any  other 
cord  up,  it  would  lead  us 
finally  into  the  spinal  cord 
or  the  brain.  Most  of  these 
white  cords,  which  are  the 
nerves,  have  one  end  divided 
into  the  finest  of  fibers  in 
the  different  parts  of  the 
body,  and  the  other  end  in 
the  spinal  cord  or  brain. 
The  brain  and  spinal  cord  are  called  the  nerve  centers. 

12.  By  examination  with  the   microscope,  it  is  found 


Fig.  56. 
NERVE-CELLS  (Magnified). 


THE  NERVOUS   SYSTEM. 


147 


that  the  gray  part  of  the  brain  and  spinal  cord  is  partly 
made  of  cells  of  various  shapes,  with  fibers  running  out 
of  them.  The  white  matter  is  made  of  nerve  fibers  lying 
side  by  side.  The  nerves  consist  entirely  of  white  nerve 
fibers.  Most  of  the  gray  matter  with  its  cells  is  found 
in  the  nerve  centers. 


ACTION  OF  THE  NERVOUS 
SYSTEM. 

SECTION  II.  — 1,  If 
nerves  are  cut  off,  we  shall 
find  a  great  change  in 
the  parts  to  which  they 
go.  If  all  the  nerves 
going  to  a  particular  part 
of  the  skin  are  cut  off, 
that  part  of  the  skin  will 
be  insensible.  You  may 
prick  or  pinch  it,  and  it 
will  not  feel.  If  all  the 
nerves  going  to  a  muscle 
are  cut  off,  that  muscle 
will  not  obey  your  will: 
you  can  no  longer  use  it. 

2,  What  you  have  done 
has  not  injured  directly 
the  skin  or  the  muscle. 
It  has  cut  off  their  con- 
nection with  the 
centers. 


Fig.  57. 

NERVES   OF   THE  SHOULDER  AND  ARM.— 
1.  Artery.    2.  Nerves. 


nerve 

We  infer,  therefore,  that  it  is  not  really  the 
skin  that  feels  when  we  prick  it.  It  is  something  in 
the  nerve  centers,  and  the  nerve  is  the  road  by  which  the 


148  THE   HUMAN   BODY. 

effect  of  the  prick  gets  to  the  centers.  When  that  road  is 
cut  off,  we  feel  nothing.  We  infer,  also,  that  the  muscle 
does  not  commonly  move  of  itself. 
It  is  caused  to  move  by  something 
in  the  nerve  centers,  and  the  nerve 
is  the  road  by  which  the  influence 
from  the  center  that  makes  it  move 
gets  to  it. 

3.  The  nervous  system  may  be 
compared  to  the  telegraphic  sys- 
tem of  a  railroad.  The  nerves  are 
the  wires.  The  gray  matter  of  the 
spinal  cord  contains  the  offices  of 
the  district  superintendents.  In 
the  cerebrum  is  the  office  of  the 
superintendent  of  the  road.  Sup- 
pose a  mosquito  lights  on  your  face, 
and  puts  in  his  bill.  He  can  not 
put  it  in,  small  as  it  is,  without  hit- 
ting one  or  more  little  nerve  fibers. 
Instantly  a  message  goes  along 
those  nerve  fibers,  through  the 
nerve-trunks,  through  the  spinal 
cord,  and  finally  to  the  general 
superintendent's  office.  The  mes- 
NERVES  OF  THE  FORE-ARM  AND  gage  js  "  Something  wrong  here." 

HAND.  — 1.  Artery.    2.  Nerves.  _ 

Immediately  an  order  is  sent  out, 

along  other  nerve  trunks  and  fibers,  to 'the  muscles  of  the 
shoulder  and  arm ;  and  they  contract,  so  as  to  strike  the 
mosquito. 

4.    This  is  done  very  quickly,  and  yet  it  takes  some  time. 
The  message  goes  in  at  the  rate  of  one  hundred  and  forty 


THE  NERVOUS   SYSTEM.  149 

feet  in  a  second ;  it  goes  out  at  the  rate  of  about  ninety  feet 
in  a  second ;  and  it  takes  a  little  time  for  the  superintend- 
ent to  receive  the  message,  and  give  the  order.  Then  it 
takes  time  for  the  muscles  to  contract. 

If  the  mosquito  is  quick,  he  will  escape  you. 

REFLEX   ACTION. 

5,  In  the  night,  the  general  superintendent's  office  is 
closed :  the  cerebrum  is  asleep.     And  yet,  if  the  foot  is 
pricked  or  tickled,  it  will  be  drawn  up.     A  frog's  brain 
may  be  taken  out  entirely,  without  killing  him.     If  then 
his  side  is  pricked,  he  will  scratch  it  with  his  foot.     This 
shows  us  that  the  general  superintendent  in  the  cerebrum 
does  not  do  all  the  regulating  of  the  body.     There  are 
district  superintendents   in  the  spinal  cord,  and  in  the 
medulla ;   and  some  matters  are  never  sent  up  to  the  cen- 
tral office  at  all.     Digestion  and  respiration  and  circula- 
tion are  all  regulated  by  district  superintendents. 

6,  Such  actions  are  called  reflex  actions;  because  the 
message  is  sent  in,  and  the  order  for  the  act  "  reflected  " 
back,  without  any  action  of  the  will. 

Winking  is  ordinarily  a  reflex  act.  The  eye  gets  a 
little  dry.  The  message  goes  in  along  the  nerve  fibers, 
which  end  just  beneath  its  surface ;  and  the  order  comes 
out  to  a  muscle  which  brings  the  lids  together,  and  spreads 
moisture  over  the  eye. 

Coughing  is  a  reflex  act.  Something  tickles  the  throat, 
or  the  air-passages  below;  and  we  can  not  help  coughing. 
The  muscles  of  expiration  combine  to  throw  out  the  thing 
that  tickles. 

Sneezing  is  a  reflex  act,  for  the  purpose  of  clearing  the 
air-passages  above  the  throat.  All  these  acts  are  regulated 
by  centers  below  the  cerebrum. 


150  THE  HUMAN  BODY. 

7.  Many  actions  which  must,  at  first,  be  attended  to  by 
the  cerebrum,  may,  after  a  time,  be  handed  over  to  the 
offices  lower  down.     For  example,  in  learning  to  play  on 
the  piano,  it  is  necessary,  at  first,  to  give  the  whole  mind 
to  every  touch.     After  a  while,  difficult  music   can   be 
played  with  little  thought. 

If  we  were  not  made  so  that  we  could  act  in  this  way, 
our  whole  time  and  attention  would  be  taken  up  in  doing 
the  things  which  now  seem  the  simplest.  Our  minds  would 
be  worn  out  in  making  the  movements,  and  combinations 
of  movements,  necessary  in  eating  and  breathing  and 
walking. 

8,  The  nerve-fibers  which   carry  messages  in  to   the 
centers  are  called  sensory  fibers.     The  nerve  fibers  which 
carry  messages  out  to  the  muscles  are  called  motor  fibers. 

9.  The  messages  do  not  all  come  from  the  outside,  as  in 
the  case  of  the  mosquito-bite.     A  wish  or  thought  may 
start  in  the  cerebrum,  without  any  impression  from  out- 
side, and  cause  an  order  to  be  sent  out  to  the  muscles. 

10,  The  nervous  system  connects  the  different  parts  of 
the  body,  and  makes  them  work  together. 

THE   CEREBRUM   THE   SEAT   OP   THE   HIGHER   FACULTIES. 

SECTION  III. —  1,  We  have  taken  it  for  granted,  that 
the  cerebrum  is  the  seat  of  the  higher  faculties, — the 
memory,  the  reason,  the  will,  the  feelings.  This  is  proved 
in  two  ways :  — 

i.  If  this  portion  of  the  brain  be  diseased  or  injured, 
these  faculties  are  affected. 

g.  The  more  of  the  higher  faculties  an  animal  has,  the 
larger  is  the  cerebrum  in  proportion  to  the  rest  of  the 
brain.  Man  has  the  largest  cerebrum  proportionally. 


THE  NERVOUS  SYSTEM.  151 

SECTION  IV.  —  1,  We  say  that  a  person  is  nervous  when 
his  nervous  system  is  excited  by  trifling  matters.  Sick- 
ness makes  people  nervous.  Close  rooms  and  bad  air  make 
people  nervous.  Lack  of  exercise  makes  people  nervous. 
Indigestible  food  makes  people  nervous.  The  nervous 
system  will  endure  a  great  deal  of  wear  if  rightly  treated. 
Lack  of  sleep,  too  much  excitement,  and  anxiety,  often 
break  it  down.  Worry  is  much  more  wearing  than 
work.  Stimulants,  which  spur  the  nerves  continually, 
finally  prostrate  them. 

2,  Actions  at  first  done  with  care  and  thought,  by  being 
done  frequently,  are  at  length  done  without  effort.     They 
become  partly  reflex  acts.      That  is  the  reason  why  a 
skilled  workman  can  work  so  much  longer  without  being 
tired  than  a  stronger  man  could,  who  was  not  so  skill- 
ful.    In  this  way  good  habits  help  us,  —  good  habits  of 
position,  of  movement,  of  speech,  of  study.    So  bad  habits 
make  slaves  of  us.     The  habit  of  biting  the  nails  is,  in 
many  persons,  a  reflex  act,  which  it  is  difficult  to  refrain 
from,  because  it  is  done  without  thought. 

3.  The  brain  needs  exercise  just  as  truly  as  the  muscles. 
Study  and  thought  not  only  make  the  brain  strong  and 
clear:  they  help  to  keep  it  in  good  health. 

EFFECTS  OF  ALCOHOL  ON  THE  NERVOUS  SYSTEM. 

SECTION  V. — 1.  Alcoholic  drinks  are  used  chiefly  for 
their  effects  on  the  nerves  and  brain.  They  stimulate  the 
sense  of  taste  in  the  tongue  and  palate,  and  they  warm  the 
stomach.  Without  really  increasing  strength,  they  give  a 
feeling  of  strength  and  confidence.  In  moderate  doses, 
they  excite  the  braiii.  The  sensibilities  become  lively, 
ideas  flow  readily,  wit  seems  brighter,  and  philosophy 


152  THE  HUMAN  BODY. 

more  profound.  The  nerves  that  control  the  muscles  are 
but  little  affected  at  this  stage,  and  yet  they  are  disturbed. 
A  very  little  wine  may  spoil  the  chances  of  a  rifleman  in 
a  shooting-match,  or  of  a  player  in  a  game  of  ball. 

2,  As  the  amount  of  alcohol  is  increased,  the  higher 
faculties  of  the  mind  grow  dull,  while  the  lower  propensi- 
ties are  still  further  excited.     That  portion  of  the  brain 
which  presides  over  the  muscles  loses  its  control.     They 
still  act  with  force ;  but  they  have  no  guide,  and  they  do 
not  act  together.    A  drunken  man  can  strike  a  hard  blow, 
but  he  can  not  hit  straight.     The  muscles  of  his  legs  fail 
to  combine  their  action.     They  are  all  at  cross-purposes, 
each  contracting  and  relaxing  without  the  direction  of  a 
central  power.     The  man's  movements  become  as  tangled 
as  his  thoughts. 

3,  Vanity  and  pugnacity  are  now  aroused ;  recklessness 
displaces  caution ;  finally  all  self-control  is  lost,  and  the 
lowest  instincts  rule.     Ungoverned  impulses  lead  to  crime 
and  violence.     The  final  stage  is  the  drunken  sleep. 

The  course  of  events  varies  with  different  temperaments. 
Some  are  but  little  excited,  but  gradually  become  stupid; 
some  never  lose  control  of  their  limbs;  some  are  good- 
riatured;  and  some  uniformly  morose.  All  are  for  the 
time  insane. 

4,  The  after-effects  of  free  indulgence  in  alcoholic  drinks 
are,  an  aching  head,  a  foul  stomach,  unsteady  nerves,  and 
depression  of  spirits. 

Drinkers  often  reach  a  condition  in  which  this  depres- 
sion is  constant,  except  when  they  are  under  the  influence 
of  liquor. 

The  appetite  in  many  cases  grows  by  gratification.  It 
becomes  so  strong  that  it  is  almost  impossible  to  resist  it: 


THE  NERVOUS  SYSTEM.  153 

conscience  is  powerless;  ambition,  pride,  and  self-respect 
are  abandoned.  The  most  sacred  affections  are  trampled 
under  foot  to  satisfy  the  thirst.  This  condition  is  disease, 
but  it  is  a  disease  for  which  the  victim  is  himself  re- 
sponsible. 

5,  One  of  the  most  marked  effects  of  alcohol  is  an  en- 
largement of  the  small  blood-vessels.     This  is  what  makes 
a  toper's  face  red.      Not  only  in  the  face,  but  in  other 
parts,  this  enlargement  takes  place.     Alcohol  does  it  by 
paralyzing  the  little  nerves,  which  are  the  regulators  of 
the  size  of  the  vessels.      These  nerves  constitute  a  very 
delicate  mechanism  of  Nature's  contriving,  and  it  is  im- 
portant to  the  health  of  the  body  that  it  should  not  be 
interfered  with. 

6,  Alcohol  taken  into  the  stomach  is  rapidly  diffused 
through  the  body  by  the  blood.     Various  experiments 
have  proved  that  it  accumulates  especially  in  the  brain. 
In  this  delicate  organ,  it  causes  not  only  the  temporary 
effects  already  described,  but  permanent  changes  which 
manifest  themselves  in  various  diseases.      Among  them 
are  epilepsy,  paralysis,  and  insanity. 

SUMMARY  OF  THE  ACTION  OP  ALCOHOL  ON  THE  BRAIN 

AND  NERVES. 

7,  i.  It  first  excites,  and  then  paralyzes. 

8,  The  higher  faculties  are  the  first  to  be  paralyzed, 
leaving  the  man  under  control  of  his  lower  passions. 

5.  It  obscures  the  senses,  and  impairs  the  judgment. 
4.  It  exhausts  the  whole  nervous  system,  and  leads  to 
paralysis,  epilepsy,  and  insanity. 


154  THE  HUMAN  BODY. 

QUESTIONS. 

SECTION  I.  —  1,  What  may  be  the  effects  of  injury  to  the  head? 

2.  What  may  be  the  effect  of  an  injury  to  the  back  ? 

3,  Of  what  parts  does  the  brain  consist? 

5,  What  are  the  convolutions  of  the  brain?     How  do  these  indi- 
cate the  difference  between  man  and  the  lower  animals? 

6,  7,  Describe  the  spinal  cord. 

8,  What  are  the  membranes  of  the  brain  and  cord  ?    How  many 
nerves  come  from  the  brain  ?    How  many  from  the  spinal  cord  ? 

9,  What  is  the  appearance  of  the  brain  substance?    What  is  the 
appearance  of  the  substance  of  the  spinal  cord  ? 

10,  Why  does  a  blow  on  the  funny-bone  cause  a  tingling  in  the 
little  finger  ? 

11,  What  is  the  course  of  the  nerves  outward?    What  is  the 
course  of  the  nerves  inward?    What  are  the  nerve  centers? 

12,  What  does  the  microscope  show  of  the  structure  of  the  gray 
matter?    Of  the  white  matter? 

SECTION  IT.  —  1.  What  is  the  effect  of  cutting  off  the  nerve-sup- 
ply of  a  portion  of  the  skin ?    Of  a  muscle? 

2,  What  do  we  infer  from  this  effect? 

3,  Compare  the  nervous  system  to  a  railroad  telegraph.    What 
takes  place  when  a  mosquito  stings  ? 

4,  Does  it  take  time  for  a  sensation  to  go  through  the  nerves,  or 
for  a  motor  impulse  to  return?    Do  they  go  as  fast  as  electricity? 

5,6.  What  are  reilex  actions?    Name  and  describe  some  such 
actions. 

7,  May  acts  at  first  done  by  the  cerebrum  become  reflex  acts  ? 

8,  What  are  the  sensory  fibers?    What  are  the  motor  nerve 
fibers  ? 

10,  How  does  the  nervous  system  connect  the  different  parts  of 
the  body  ? 

SECTION  III.  —  1,  How  do  we  know  that  the  cerebrum  is  the  seat 
of  the  higher  faculties  ? 

SECTION  IV.  —  1.  What  is  it  to  be  nervous?    What  makes  people 
nervous?    What  breaks  down  the  nervous  system ? 


THE  NERVOUS   SYSTEM.  155 

2,  How  do  good  habits  help  us? 

3,  Does  the  brain  need  exercise  ? 

SECTION  V.  —  1.  For  what  chiefly  are  alcoholic  drinks  used  ?  Do 
they  increase  strength?  What  is  their  first  effect  in  moderate 
amount? 

2,  3,  What  is  the  effect  if  drinking  continues  ?  Are  all  affected 
in  the  same  way  by  alcohol  ? 

4,  What  are  the  after-effects  of  free  drinking?    Is  the  appetite 
easily  controlled  ? 

5,  How  does  alcohol  make  a  toper's  face  red  ? 

6,  For  what  part  of  the  body  has   alcohol   a  special  affinity? 
What  diseases  of  the  brain  are  among  its  effects  ? 

7,  Give  a  summary  of  the  effect  of  alcohol  on  the  brain  and 
nerves. 


156  THE  HUMAN  BODY. 


CHAPTER  X. 
THE    SKIN. 

STRUCTURE   OP   THE   SKIN. 

SECTION  I.  —  1,  The  skin  is  the  covering  of  the  body. 
It  is  soft  and  smooth,  but  strong.  It  fits  perfectly  ;  but  it 
stretches  and  glides  a  little  on  the  muscles  beneath,  and, 
therefore,  does  not  hinder  our  movements,  as  close-fitting 
garments  do.  It  is  partly  transparent,  and  shows  the 
blue  color  of  the  veins,  and  the  red  of  the  arteries,  beneath 
it. 

It  becomes  quite  thick  in  places  where  a  thick  covering 
is  needed,  as  on  the  palms  of  a  laboring-man,  or  the  soles 
of  a  barefoot  boy. 

2,  If  we  prick  a  blister,  a  little  watery  fluid  comes  out, 
and  it  flattens  down.     It  does  not  hurt  to  prick  it,  and  it 
draws  no  blood.    So  we  find  that  the  top  layer  of  the  skin 
has  no  nerves  or  blood-vessels.     But,  when  we  "  scrape  the 
skin  off,"  we  are  hurt,  and  have  a  red,  bleeding  surface. 
We  do  not  often  really  scrape  the  skin  off  with  trifling  ac- 
cidents; but  we  take  off  the  top  layer,  and  get  down  to  the 
deep  layer,  which  contains  both  nerves  and  blood-vessels. 

3,  Dandruff,  which  comes  from  the  scalp,  consists  of 
dry  scales  from  the  surface  of  the  skin.     From  all  of  the 
rest  of  the  skin,  little  scales  are  constantly  coming  off. 

SUGGESTION  TO  TEACHERS.  —  Illustrate  this  chapter  by  studies  of  the  cuti- 
cle and  hairs  of  men  and  animals,  with  a  microscope.  A  lens  of  one-inch 
focus  will  show  the  pores  on  the  palm. 


THE  SKIN. 


157 


They  are  much  smaller  than  the  scales  of  dandruff,  and 

look  like  dust.     We  do  not  notice  them,  but  they  gather 

in  our  clothing;  and 

we    may    scrape    off 

some    of  them,    and 

examine 


Papillae. 


Epidermis 
or  cuticle. 


them  with 
a  microscope.  They 
appear  as  dry  white 
scales  or  flakes,  and 
they  are  really  dead 
skin.  As  this  dead 
surface  wears  off,  the 
deep  layer  must  keep 
on  growing,  to  make 
up. 

4,  The  top  layer  of 
the  skin  is  called  the 
epidermis,  or  cuticle. 
The  deep  layer  of  the 
skin  is  called  the 
derma,  or  cutis  vera 
(true  skin).  If  a  very 
thin  slice  of  skin  be 
taken  out  by  cut- 
ting straight  down 
through  it,  and  we 
look  at  it  with  a  mi- 
croscope, we  see  some- 
thing like  the  figure 
(Fig.  59).  On  the- 
line  which  joins  the 
derma  and  epidermis,  there  are  little  cones  pointing  up. 


Derma,  or 
cutis  vera. 


Fig.  59. 
SECTION  OP  SKIN. 


158 


THE  HUMAN  BODY. 


Fig.  60. 
PAPILLAE. 


These  are  called  papillae,  and  are  shown  in  larger  size  in 
Fig.  60,  in  which  the  epidermis  has 
been  stripped  off,  leaving  only  the 
derma  with  the  papillae  on  its  surface. 
In  this  way  we  sometimes  scrape  off 
the  epidermis  by  an  accident,  and 
these  papillae  show  as  little  red  points. 
They  contain  blood-vessels  and 
nerves. 

5.  The  palm  of  the  hand,  and  especially  the  ends  of 
the  fingers,  have  distinct  ridges^  with  furrows  between 
them,  which  you  can  easily  see. 

The  ridges  are  made  by  the  papil- 
lae, which  are  numerous  in  these 
parts.  When  magnified,  they 
look  like  the  figure  (Fig.  61). 

6,  The    black    spots    on     the 
ridges,  in  the  figure,  indicate  the 
mouths  of  the  sweat-ducts,  which 
are  called  pores.  In  Fig.  59  we  see 
one    of  these  sweat-ducts.     It  is 
simply  a  tube.     As  we  follow  it 
down  from  the  surface,  it  twists 
in  corkscrew  fashion  through  the 
cuticle,  and   then   takes  a  wavy 

COUrse  through  the  CUtis  Vera,  and   PAPILLARY  RIDGES  IN  THE   SKIN 
,1        -,  /.      OP  THE  PALM.  THE  BLACK  SPOTS 

terminates  in  the  deepest  part  of     AKE  THE  PoBES. 

the  skin,  or  just  beneath  it,  in  a 

coil,  which  is  the  sweat-gland.     On  the  outside  of  this  coil 

is  a  net-work  of  capillary  vessels  (Fig.  62).     From  these 

capillaries  some  of  the  water  and  salts  of  the  blood  pass 

through  into  the  tube.     As  the  tube  fills,  its  contents  well 


Fig.  61. 


THE  SKIN. 


159 


The  tubes  are  like 


up,  and  flow  over  on  the  surface, 
springs,  drawing  their  supply  from 
the  blood-vessels  beneath.  It  has 
been  estimated  that  there  are  2,500,- 
000  of  them  altogether,  and  that,  if 
they  were  all  joined  in  one  tube,  it 
would  be  ten  miles  long. 

PERSPIRATION. 


7,  We  do  not  see  any  moisture  on 
the  surface  when  we  are  cool,  but 
there  always  is  some  pouring  out 
of  the  tubes.     Ordinarily  it  changes 
into  vapor,  and  is  wafted  away  so 
fast  that  it  can  not  gather  in  drops. 
But,   when   we   are  very  warm,  it 
wells    up    so    rapidly    that    drops 

appear;  and  these  sometimes  flow  in  streams, 
remain  quiet  in  a  cool  place,  we  dry  off;  that  is,  the  per- 
spiration does  not  come  so  fast,  and  that  which  is  already 
on  the  surface  is  changed  to  vapor,  and  carried  away  by 
the  air. 

The  moisture  which  is  constantly  coming  from  the 
pores,  but  which  we  can  not  see,  is  called  insensible  per- 
spiration. That  which  we  can  see  and  feel,  as  water,  is 
called  sensible  perspiration,  or  sweat. 

HAIR. 

8.  Hairs  grow  from  the  skin.     On  most  of  the  body 
they  are  short  and  fine.     On  the  scalp  and  the  face  they 
grow  long.      The  hair  which  covers  the  bodies  of  the 
lower   animals  is  very  useful   in   keeping   them   warm. 


Fig.  62. 

SWEAT-GLAND,  WITH  CAPIL- 
LARIES SURROUNDING  IT. 


If  we 


1GO  THE  HUMAN  BODY. 

Man  does  not  need  it  for  this  purpose,  because  he  has 
intelligence  to  clothe  himself.  The  head  and  throat  are, 

however,  protected  in  this 
way.  In  Fig.  63,  we  see 
the  root  of  a  hair  as  the 
microscope  shows  it.  It  is 
in  the  true  skin,  at  the 
bottom  of  a  tube.  To  the 
lower  end  of  this  tube,  a 
muscular  fiber  is  attached, 
which  passes  up  to  the 

SECTION  OF  THE  SKIN,  SHOWING  ROOTS  OF  Surface  of  the  skin.  When 
HAIRS  -1  Muscles  attached  to  the  hair-  thj  fiber  contracts,  it  pulls 
sac.  2.  Sebaceous  glands. 

.  up  the  hair,  and  makes  the 

skin  around  it  project,  like  a  pimple.  Cold  makes  these 
fibers  contract :  so  does  fear.  It  is  in  this  way  that  the 
hair  "  stands  on  end,"  and  that  "  goose-flesh  "  is  made. 

SEBACEOUS    GLANDS. 

9.  Opening  into  the  tubes  in  which  the  hairs  stand, 
are  other  tubes,  which  come  from  little  sacs,  called  seba- 
ceous glands.     These   lie  in  the  skin,  by  the  side  of  the 
hair-tubes.     They   manufacture   an   oily  fluid,  which   is 
poured   into   the  hair-tube,  and   out  on  the  surface.     It 
keeps  the  skin  soft,  and  gives  a  moist  and  glossy  appear- 
ance to  the  hair.     When  the  scalp  is  unhealthy,  and  these 
glands  are  not  active,  the  hair  becomes  harsh  and  dull 

and  brittle. 

NAILS. 

10.  The  nails,  like  the  hairs,  grow  from  the  skin.    They 
are,  indeed,  a  bit  of  the  top  layer,  or  cuticle,  specially  har- 
dened.    It  is  desirable  that  the  ends  of  the  fingers  should 


THE   SKIN.  161 


be  firm  for  picking  and  touching;  and,  therefore,  these 
little  stiff  backs  are  made  to  grow  in  them.  The  root  of 
the  nail  is  the  upper  end  beneath  the  skin.  The  matrix 
is  the  bed  on  which  it  lies,  and  from  which  it  grows.  The 
nail  may  be  shed  or  torn  out,  and,  if  the  matrix  is  sound, 
a  new  nail  will  grow.  If  the  whole  matrix  is  destroyed, 
there  will  be  no  new  one.  But  a  very  small  portion  of 
the  matrix  remaining,  will  produce  a  new  nail,  though  it 
may  be  an  imperfect  one. 

USES   OP   THE   SKIN. 

11,  Understanding  the  structure   of  the  skin,  we  are 
ready  to  notice  its  uses. 

1.  It   protects  the    parts    beneath.      Being  tough  and 
elastic,  it  can  bear  hard  knocks.     The  cuticle,  which  is 
without  nerves,  covers   and  guards  the  sensitive  parts. 
Neither  fluids  nor  gases  pass  through  it  easily.     If  the 
skin  is  whole,  we  can  safely  put  our  hands  in  poisonous 
fluids,  which  would  enter  the  blood,  and  do  us  harm,  if  it 
were  scratched. 

2.  It  gives  off  waste  matters  from  the  body.     Perspira- 
tion is  chiefly  water,  but  it  contains  some  other  substances 
dissolved  in  it.     The  amount  of  water  given  off  in  a  day 
is  different  at  different  times  and  in  different  persons,  but 
is  ordinarily  about  a  quart.     In  this  amount  of  water,  two 
or  three  spoonfuls  of  solid  matter  are  dissolved. 

3.  It  regulates  the  heat  of  the  body. 

BODILY   HEAT. 

12,  Our  bodies  are  always  making  heat ;  and  yet,  if  we 
put  the  bulb  of  a  thermometer  in  the  mouth  of  a  healthy 
man,  it  will  never  rise  more  than  a  degree  or  two  above 


162  THE  HUMAN  BODY. 

98 J°  F.  If  it  rises  higher,  he  is  sick,  and  has  a  fever. 
Nor  will  it  fall  more  than  a  degree  or  two  below  98J°  F. 
In  the  stomach  and  in  the  blood,  the  thermometer  would 
mark  about  100°  F.,  never  rising  much  above,  or  falling 
much  below.  100°  F.  is,  then,  the  natural  temperature 
of  the  inside  of  man's  body.  If  he  live  under  the  tropi- 
cal sun,  it  will  not  rise  more  than  a  degree  or  two  above 
this  if  he  is  well;  and,  if  he  live  in  Greenland,  it  will 
not  fall  more  than  a  degree  or  two  below. 

13,  If  we  undertake  to  keep  a  room  at  a  fixed  tempera- 
ture, we  must  have  a  fire  to  warm  it ;  and  we  must  have 
means  of  cooling  it  if  it  is  too  warm.     The  human  body 
has   its   fire,  and   it   has  its  cooling-apparatus;  and  this 
heating   and   cooling   apparatus   is   self -regulating,  and 
works  so  perfectly,  that,  throughout  a  long  life,  in  heat 
and  in  cold,  the  inward  temperature  never  varies  more 
than  two  or  three  degrees  in  health. 

HOW   THE   HEAT   IS   MADE   EQUAL,   IN   ALL,   PARTS. 

14,  The  fire  is  not  in  any  one  part,  but  in  all  parts.    In 
every  particle,  the  changes  which  take  place,  as  the  parti- 
cle takes  up  oxygen  from  the  blood,  and  gives  out  car- 
bonic acid,  make  heat,  as  the  changes  which  take  place  in 
the  coal  or  wood  in  the  stove  make  heat.     This  heat  is 
given  to  the  blood.      It  is  warmer  when  it  comes  from 
the  capillaries,  where  it  has  been  in  close  contact  with  the 
particles ;  and  the  blood,  now  divided  in  a  thousand  little 
streams,  and  again  united  in  one  stream,  at  the  heart, 
diffuses  the  heat  through  the  body. 

15,  Suppose  the  feet,  for  example,  to  be  more  exposed 
to  cold  than  other  parts.     The  blood  in  the  feet  might  be, 
for  a  very  short  time,  colder  than  the  rest  of  the  body ; 


THE   SKIN.  163 


but  that  blood  immediately  passes  upward,  and  is  warmed 
by  the  warmer  stream  above,  with  which  it  is  mixed.  A 
fresh  supply  of  warm  blood  comes  down,  and  contributes 
its  heat  to  the  feet.  They  are  enabled  in  this  way  to 
maintain  nearly  the  same  heat  as  the  rest  of  the  body. 

On  the  other  hand,  suppose  the  brain  or  the  stomach, 
while  they  are  especially  busy,  to  grow  hotter  than  the 
rest  of  the  body.  Their  heated  blood  is  soon  mingled  with 
the  general  stream ;  and,  while  it  helps  to  heat  the  rest,  is 
itself  cooled.  The  heated  parts  are  cooled  by  the  cooler 
blood  coming  from  other  parts.  So,  by  the  constant  cir- 
culation of  the  blood,  the  heat  of  all  parts  is  made  nearly 
equal. 

16,  The  air  is  ordinarily  cooler  than  the  body,  and  is 
constantly  taking  heat  from  it.     Clothing  keeps  us  from 
losing  heat  too  fast.     Furs  and  woolens  have  no  warmth 
in  themselves.     They  only  keep  off  the  cold  air,  and  keep 
in  the  heat  that  the  body  makes.     Besides  this,  in  cold 
weather,  we  warm  the  air  by  fires. 

If  we  are  much  out  of  doors  in  cold  weather,  two  things 
help  us  to  keep  warm :  — 

i.  We  eat  more,  and  so  furnish  more  fuel  to  our  inter- 
nal fires.  We  also  get  more  oxygen  in  each  breath,  and 
this  is  fuel  too. 

s.  We  exercise  more,  and  that  keeps  these  internal  fires 
more  active. 

In  these  ways,  more  heat  is  made ;  and  we  can  afford  to 
lose  more. 

HOW   THE   BODY   IS    COOLED. 

17,  Sometimes  there  is  too  much   heat  in  our   bodies, 
as  when  we  are  exercising,  or  in  the  sun.     It  will  not  go 
off  into  the  air  fast  enough,  even  if  we  are  lightly  clothed. 


164  THE  HUMAN  BODY. 

In  that  case,  the  skin  becomes  a  cooling-apparatus.  It 
works  in  two  ways :  — 

1.  The  deep  layer  of  the  skin  is  full  of  small  blood- 
vessels. The  effect  of  heat  is  to  make  these  blood-vessels 
grow  larger.  The  blood,  then,  flows  into  them,  away  from 
the  deeper  vessels.  That  is  the  reason  your  face  gets  red 
when  you  are  heated.  While  the  blood  is  in  these  vessels 
of  the  skin,  it  grows  cool  much  faster  than  it  does  when  it 
is  deep  in  the  body.  It  is  nearer  the  cool  air.  The  skin, 
then,  receives  more  blood  when  we  are  heated,  and  spreads 
it  out  in  a  thin  layer  near  the  surface,  and  so  cools  it.  By 
cooling  the  blood,  the  whole  body  is  cooled. 

s.  The  two  or  three  million  sweat-glands  do  a  most 
important  part  of  the  regulation  of  the  heat  of  the  body. 

In  cities,  water-carts  go  about  in  hot  weather  sprinkling 
the  streets.  This  lays  the  dust,  and  cools  the  air.  Much 
of  the  sprinkled  water  evaporates  as  it  touches  the  warm 
stones ;  and,  wherever  water  evaporates,  it  makes  things 
around  it  a  little  cooler.  The  sweat-glands  form  a  great 
watering-apparatus  for  the  surface  of  the  skin.  The  per- 
spiration evaporates ;  and  the  skin,  and  the  blood  in  it,  are 
cooled.  The  hotter  it  is,  the  more  we  perspire ;  and,  the 
more  we  perspire,  the  more  heat  is  taken  away.  Men  can 
stay  for  a  time  in  a  temperature  of  200°  F.,  and  even  more 
if  they  perspire  freely.  If  perspiration  is  checked,  they 
can  not  easily  endur©  even  a  moderate  heat.  The  reason 
why  we  suffer  more  from  heat  in  what  we  call  a  "  sticky 
day"  in  summer,  is  that  the  air  is  moist,  and  does  not  take 
up  the  moisture  from  the  skin  so  fast  as  drier  air  would. 
Our  bodies  are  wet,  and  evaporation  goes  on  slowly. 

SUGGESTION  TO  TEACHERS. — Show  the  cooling  effect  of  evaporation  by 
throwing  a  spray  of  alcohol  or  ether  on  the  hand,  with  an  atomizer. 


THE  SKIN.  165 


CARE  OF  THE  SKIN. 

SECTION  II.  —  1,  If  the  skin  of  an  animal  is  covered 
with  varnish,  it  will  soon  die.  If  more  than  half  of  the 
surface  of  the  skin  is  burned,  even  though  the  burn  be 
not  very  deep,  death  will  probably  be  the  result.  This 
shows  how  important  the  action  of  the  skin  is.  It  should 
be  well  taken  care  of. 

2,    To  keep  the  skin  healthy,  three  things  are  needed :  — 

1,  To   keep    the    glands  (sweat-glands    and    sebaceous 
glands)  open  and  active. 

2,  To  keep  the  blood  circulating  freely  in  it. 
s.  To  let  the  air  get  to  it. 

3,  The  solid  matter  in  the  perspiration,  the  oily  matter 
from  the  sebaceous  glands,  and  dead  scales  from  the  sur- 
face, together  with  dirt,  will  form  a  thin  coating,  which 
clogs  the  pores,  and  is  itself  unwholesome. 

The  skin  of  a  savage  is  freely  exposed  to  air.  The 
civilized  man,  stepping  from  a  warm  bed  into  warm 
clothing,  and  staying,  perhaps,  much  of  his  time  in  close 
rooms,  gets  a  soft,  over-sensitive  skin.  Neither  its  glands 
nor  its  blood-vessels  are  vigorous,  and  it  can  not  do  its 
work  well. 

4,  Besides,  such  a  man  is  liable  to  colds.     A  cold  gen- 
erally comes   from   chilling   some   portion   of  the  skin. 
Those  who  are  out  of  doors  in  all  weather  do  not  often 
catch  cold.     Their  skin,  as  well  as  the  rest  of  the  body, 
can  better  resist  a  chill.     Those  who  are  seldom  exposed 
to  cold  air,  and  whose  skin  has  become  delicate,  catch 
cold  most  readily. 

5,  Too  thick   clothing   keeps  air  from  the  skin,  and 
weakens  it  by  keeping  it  too  warm.     Air-baths  are  useful. 


166  THE  HUMAN  KODY. 

6,  People  who  are  sick  or  in  pain,  often  receive  great 
relief  and  comfort  from  having   the  skin  rubbed;   and 
it  not  only  relieves,  but,  when  thoroughly  and   perse- 
veringly  done,  it  helps  to  cure  many  diseases.     It  is  good 
for  well   people   also.      Thorough  friction   of  the  whole 
body  with  a  brush  or  a  dry  towel  every  morning,  is  the 
next  best  thing  to  a  daily  bath.     It  exercises  the  muscles 
of  the  skin.     It  brings  the  blood  into  it.     It  removes  the 
accumulations  of  dead  cuticle  and  perspiration. 

7,  No  other  one  thing  is  so  important  for  the  health  of 
the  skin  as  bathing.     It  is  possible  for  a  delicate  person 
to  bathe  too  much,  and  imprudent  bathing  is  sometimes 
hurtful.     But,  practiced  with  discretion,  it  is  of  great  ad- 
vantage.    True,  very  many  people  enjoy  good  health  who 
never  bathe.     But  it  seems  unnecessary  to  argue,  that  to 
keep  the  skin  clean,  the  pores  open,  the  glands  active,  and 
the  circulation  free,  by  water  and  rubbing  combined,  must 
make  the  skin,  and  therefore  the  whole  body,  more  healthy. 

8,  Cold  water  is  a  natural  stimulant  of  the  skin.     The 
slight  shock  that  it  gives  to  the  nervous  system  rouses  the 
whole  body  to   greater  activity.      Salt-water  bathing   is 
more  invigorating  than  fresh-water  bathing,  because  the 
salt  has  a  direct,  stimulating  effect  of  its  own. 

9,  There  is  no  other  safeguard  against  colds  so  good  as 
a  daily  bath.     We  take  cold  because  the  skin  is  sensitive 
and  delicate,  and  will  not  bear  exposure  to  the  damp  or 
chilly  air.     By  regular  bathing,  it  is  made  vigorous,  the 
blood  flows  freely  through  it,  and  its  nerves  are  strength- 
ened, so  that  we  do  not  get  chilled. 

For  that  very  common  affection,  catarrh,  cold  water, 
used  freely  and  regularly  on  the  skin,  is  an  excellent 
remedy. 


THE  SKIN. 


167 


10.    Certain  cautions  are  to  be  observed  in  bathing :  — 

1.  Never  bathe  directly  after  a  full  meal.      The  blood 
is   then   directed  -to   the    stomach,   and   active   work   is 
going  on   there.     Other  organs  are  relaxed.     The  bath 
will  hinder  digestion,  and  sometimes  cause  an  injurious 
shock. 

s.  Never  bathe  in  cold  water  when  the  system  is  greatly 
exhausted.  Very  delicate  persons  should  not  bathe  in 
cold  water  at  all. 

8.  Be  very  cautious  about  bathing  in  cold  water  when 
heated,  especially  if  you  are  at  the  same  time  tired. 

4.  Never  stay  in  the  water  until  you  are  chilled,  so 
that  you  do  not  get  warm  soon  on  coming  out,  or  until 
you  feel  languid  and  weak  instead  of  feeling  refreshed. 

Great  injury  sometimes  results 
from  neglect  of  these  rules. 

THE   EAR. 

SECTION  III.  —  1,  The  ear, 
like  the  nose,  is  partly  outside, 
and  partly  inside,  of  the  head. 
It  may  be  divided  into  — 

The  External  Ear. 

The  Middle  Ear. 

The  Internal  Ear. 

2,  The  external  ear  is  like  an 
ear-trumpet;  and  its  design  is  to 

collect  the  sound,  and  carry  it  in  THE  EAR. -i'1>arts  of  the  extent 
toward  the   internal   ear,  where     eai-    2-  Part8  of  the  middle  ear. 

.,  .,  ,  .  T  .,  3.  Parts  of  the  internal  ear. 

the  nerve  of  hearing  is.     Like  an 

ear-trumpet,  it  has  an  open  part  and  a  tube.     The  tube 

enters  the  head :  the  open  part  is  on  the  outside.     It  is 


108  777 E  HUMAN   I1ODY. 

made  chiefly  of  cartilage.  There  are  three  little  muscles 
attached  to  the  external  ear,  and  some  people  can  move 
it.  Most  people  can  not. 

3,  The  tube  is  called  the  external  auditory  canal.     It 
is  an  inch  long,  and  ends  at  the  membrane  of  the  tym- 
panum. 

4,  The  membrane  of  the  tympanum,  or  drum-head,  sepa- 
rates the  middle  from  the  external  ear.     The  cavity  of 
the  middle  ear  is  called  the  tympanum,  or  drum.     It  con- 
tains the  small  bones  of  the  ear.     It  is  connected  with 
the  back  part  of  the  throat  by  a  tube,  called  the  Eustachian 
tube. 

5,  The  internal  ear  is  beyond  the  middle  ear,  deep  in  a 
bone  of  the  skull.     In  it  are  the  endings  of  the  nerve  of 
hearing. 

HOW   WE  HEAR. 

6,  Sound  is    a   vibration  which  can   be  perceived  by 
the  ear.     Commonly  as  it  reaches  the  ear  it  is  a  vibra- 
tion of  the  air.     The  waves  of 
air  enter  the  external  auditory 
canal,   and    strike    the    drum- 
head.    They  make   the   drum- 
head vibrate. 

7.   Across  the  cavity  of  the 
drum,  from  the  drum-head  to 
Fi    65  the    opposite    wall,    the    three 

BONES  OF  THE  LEFT  EAR,  SEEN    little   bones   of  the   ear  —  the 

FROM  THE  INSIDE. -1.  Hammer       «  hammer  "     the     "  Elivil  "      Elld 
2.  Anvil,    a.  Stirrup.   4.  Stapedius. 

the   "stirrup     — are   stretched 

in  a  chain.  The  hammer  is  joined  to  the  drum-head 
and  to  the  anvil,  and  the  anvil  to  the  stirrup. 

8,    When  the  drum-membrane  vibrates,  these  little  bones 


THE   SKIN.  169 


are  made  to  vibrate.  The  last  one  in  the  chain,  the  stirrup, 
is  joined  to  a  small  membrane  in  the  inner  wall  of  the 
drum,  which  is  like  a  little  drum-head.  On  the  other  side 
of  this  little  drum-head  is  the  inner  ear,  which  is  filled 
with  water.  As  the  stirrup  vibrates,  it  sets  the  little 
drum-head  vibrating;  and  that  makes  the  water  in  the 
inner  ear  vibrate,  and  the  little  waves  strike  the  ends  of 
the  nerve  of  hearing,  and  by  it  the  impression  is  carried 
in  to  the  brain. 

9,    It  is  not  the  ear  that  hears.     It  is  the  brain  that 
hears  by  means  of  the  ear. 

7,  An  ear-ache  is  commonly  caused  by  inflammation  of 
the  lining  of  the  drum.     It  swells,  and  discharges  a  fluid 
that  fills  the  cavity,  and  makes  pain  by  pressure.     Some- 
times, as  the  inflammation  subsides,  the  fluid  is  absorbed. 
Sometimes  the  drum-membrane  bursts,  and  lets  out  the 
fluid ;  and  the  pain  stops.    A  discharge  from  the  ear  com- 
monly comes  from  an  inflamed  middle  ear  through  a  hole 
in  the  drum-head.     If  the  hole  is  small,  it  may  heal  up 
when  the  discharge  stops.     If  a  large  part  of  the  drum- 
membrane  is  gone,  it  will  not  heal  up. 

8,  The  loss  of  the  drum-head  does  not  destroy  the  hear- 
ing, but  it  impairs  it. 

9,  Ear-iuax  is  made  by  glands  in  the  skin  lining  the 
auditory  canal.    It  is  not  a  safe  practice  to  dig  it  out  with 
hair-pins  or  other  instruments.     Ear-wax  is  necessary  to 
keep  the  canal  and  drum-head  soft  and  moist,  and  it  will 
take  care  of  itself.     If  it  forms  hard  lumps,  and  stops  the 
ear,  as  it  sometimes  does,  it  may  be  removed  by  syringing 
with  warm  water.     No  one  but  a  physician  should  put  in 
any  instrument. 

J 


170  THE  HUMAN  BODY. 


THE   EYE. 

SECTION  IV.  — 1.  The  cavities  in  the  skull  which  con- 
tain the  eyes  are  called  the  orbits.  They  are  shaped  like 

pyramids,  pointing  inward, 
and  are  about  an  inch  and 
a  half  deep.  At  the  bottom 
of  the  orbits  are  holes, 
through  which  the  nerves 
of  the  eye  —  the  optic  nerves 
—  enter  them.  In  the  inner 
side  of  the  orbits  are  open- 
ings  into  a  canal,  called  the 
lachrymal  canal,  which  runs 
straight  down  into  the  nose. 

2,  The  orbit  is  lined  with   fat,  which   makes   a  soft 
cushion  for  the  eyeball.     The  .eyeball  is  nearly  round, 
and  about  an  inch  in  diameter.     It  is  attached  to  the 
optic  nerve  behind,  as  to  a  stem. 

3,  The  outer  coat  of  the  eyeball  is  white  and  tough. 
It  is  called  the  sclerotic  coat.     A  transparent  circle,  like  a 
watch-glass,  is  set  into  this   in  front.     It  is   called  the 
cornea. 

4,  The  cavity  of  the  eyeball  is  divided  into  two  cham- 
bers by  the  lens.     The  chamber  behind  the  lens  is  filled 
with  a  jelly-like  fluid,  called  the  vitreous  humor.     The 
chamber  before  the  lens  is  filled  with  a  watery  fluid,  called 
the  aqueous  humor. 

The  optic  nerve  goes  to  the  interior  of  the  ball,  and 
spreads  out,  by  dividing  up  into  fine  threads,  to  line  the 
back  part.  This  lining  is  the  retina. 

SUGGESTION  TO  TEACHERS.  —  Get  a  beefs  eye  from  the  butcher's,  and  dis- 
sect it. 


THE  SKIN. 


171 


5,  Looking  through  the  transparent  cornea,  we  see  the 
iris,  the  colored  part.     It  is  very  smooth  and  beautiful. 
It  is  made  partly  of  muscle  fibers, 

of  the  kind  not  subject  to  the  will. 
Some  of  them  form  circles  around 
its  center :  others  run  from  center 
to  edge,  like  the  spokes  of  a  wheel. 
When  these  latter  fibers  contract, 
the  hole  in  the  center,  called  the 
pupil,  grows  large.  When  the  cir- 
cular fibers  contract,  the  pupil 
grows  small.  The  iris  is  a  cur- 
tain for  the  eye.  Bright  light 
makes  it  close  up  the  pupil  as 
much  as  possible.  Opium  and 
some  other  drugs  will  produce 
the  same  effect.  Dim  light  makes 
it  open  the  pupil.  Belladonna 
produces  the  same  effect. 

The  contractions  of  the  iris  are 
good  illustrations  of  reflex  actions. 

6,  The  lids  have  each   a  thin 

plate  of  cartilage  in  them,  to  make  them  firm.  The  inside 
of  each  lid  and  the  surface  of  the  eye  are  covered  with  a 
mucous  membrane,  called  the  conjunctiva.  The  hairs 
(eyelashes)  which  grow  from  their  edges  help  to  protect  the 
eye  from  dust  and  perspiration.  Little  sebaceous  glands, 
called  Meibomian  glands,  lie  under  the  lining  of  the  lids, 
and  open  on  their  edges.  They  oil  the  eyelashes  and 
the  edges  of  the  lids.  Under  the  roof  of  the  outer  part 
of  the  orbit,  resting  upon  the  eye-ball,  is  the  tear-gland 
(lachrymal  gland).  About  a  dozen  little  ducts  from  it  open 


Fig.  67. 

SECTION  OF  THE  FRONT  OF  THE 
EYE.—  1.  Sclerotic.  2.  Cornea. 
3.  Anterior  chamber.  4.  Pos- 
terior chamber.  5.  Iris.  6.  Lens. 


172 


THE   HUMAN   HODY. 


on   the    surface   of  the   eye.     This  gland   furnishes   the 

moisture  which  the  eye  requires. 
By  winking,  the  moisture  is 
spread  over  the  surface. 

7,  Ordinarily  moisture  is  sup- 
plied only  as  fast  as  it  is  needed, 
and  it  all  evaporates.  In  strong 
feelings  of  sorrow  or  joy,  moist- 
ure is  poured  out  very  rapidly, 
and  gathers  in  tears.  Near  the 
inner  angle  of  the  eye,  an  open- 
ing, apparently  about  as  large 
as  a  needle,  can  be  seen  on  the 
Fig  68  edge  of  each  lid.  These  are 

LACHRYMAL  APPARATUS. -1.  Lach-  the  Openings  of  the  ducts  which 
rymal  gland.  2.  Tear-passages.  carry  Qff  faQ  tearg  rph  ^j 
3.  Lachrymal  eac.  4.  Nasal  duct.  .  .  ,  . 

into  a  sac  in  the  inner  corner 

of  the  orbit  (the  lachrymal  sac) ;  and  that  opens  into  the 
nasal  duct,  which  runs  through  the  lachrymal  canal  into 
the  nose.  When  tears  are  very  abundant,  they  overflow 
on  the  face. 

8,  There  are  six  muscles 
attached  to  the  eyeball. 
One  rolls  it  up,  one  down, 
one  out,  one  in,  and  two 
roll  it  on  an  axis  passing 
from  before  backward. 


HOW  WE  SEE. 

9,   The  eye  is  like  the 
camera  with  which  a  photographer  takes  pictures. 


Fig.  69.       2 

MUSCLES  OF  THE  EYE-BALL.  —  1.  Muscle 
of  the  upper  lid.  2.  Muscles  of  the  ball. 
3.  Optic  nerve. 


The 


SUGGESTION  TO  TEACHERS.  —  Show  and  describe  the  parts  of  a  camera. 


THE  SKIN.  173 


lens  is  like  the  glass  lens  in  the  end  of  the  tube.  The 
lining  of  the  cavity  of  the  eye-ball  is  colored  dark,  like 
the  inside  of  the  box  of  the  camera.  The  retina  is  like 
the  sensitive  plate  which  the  photographer  puts  in  just 
before  he  takes  the  picture.  The  brain  behind  the  eye 
is  represented  by  the  photographer  himself  looking 
through  from  behind  his  instrument. 

10,  When  we  look  at  an  object,  a  picture  of  it  is  made 
on  the  retina.     This  picture  can  be  seen  by  a  skillful  ob- 
server looking  into  the  eye  with  an  instrument  called  an 
ophthalmoscope.     It  may  be  seen  by  looking  from  behind 
through  an  eye  taken  from  an  animal  just  killed,  as  the 
photographer  looks  through  his  camera. 

The  retina,  which  is  the  ending  of  the  optic  nerve, 
carries  in  to  the  brain  the  impression  which  makes  the 
picture.  It  is  not  the  eye  that  sees.  If  the  optic  nerve  is 
cut  off,  we  do  not  see;  although  a  picture  will  still  be 
formed  on  the  retina  as  before.  It  is  the  brain  that  sees. 
The  eye  is  its  instrument. 

CAUSES  OP  TROUBLE  IN  THE  EYE. 

11,  The  eye  is  sometimes  weak,  and  gets  very  tired 
and  sore  by  use,  simply  because  the  whole  body  is  weak. 
But  generally  when  there  is  redness,  swelling,  or  pain  in 
the  eye,  there  is  something  wrong  in  itself.     It  may  be 
that  the  delicate   lining  of  the   lids,  the  conjunctiva,  is 
inflamed,  just  as  the  lining  of  the  throat  is  inflamed  at 
times.     The  lids  then  feel  rough,  as  if  there  were  sand 
under  them.  „ 

TOO   LONG   SIGHT. 

12,  One  of  the  commonest  causes  of  aching  eyes  and 
head,  after  reading,  is  too  long  sight.    When  we  look  at  a 


174  THE  HUMAN   KODY. 

hear  object,  the  shape  of  the  lens  is  changed  a  little  by 
an  effort  of  the  eye.  Too  long-sighted  eyes  have  to 
make  more  effort  to  do  this  than  eyes  with  natural  sight. 
The  strain  tires  and  irritates  them,  and  may  make  them 
very  weak.  This  trouble  can  be  entirely  relieved  by 
glasses. 

TOO   SHORT   SIGHT. 

13.  Short-sighted  persons  do  not  commonly  have  ach- 
ing and  inflamed  eyes.     Their  eyes  do  not  have  to  make 
the  effort  that  those   of  long-sighted   people   do   to  see 
near  objects.     Reading  does  not  tire  them.     But  short- 
sightedness is  liable  to  increase.     It  makes  the  vision  of 
every  thing  more  than  a  few  feet  away  indistinct.    It  may 
be  remedied  by  glasses,  but  they  are  an  inconvenient 
necessity. 

14.  Too  short  sight  is  very  common  among  students. 
It  is  found,  that,  when  children  begin  to  go  to  school,  few 
of  them  are  short-sighted.    In  each  higher  class,  there  are 
more  short-sighted  pupils;  and  the  number  increases  so 
fast,  that  we  infer  that  there  is  something  in  the  habits 
of  school-children  that  makes  them  short-sighted. 

CAUSES   OP   TOO   SHORT   SIGHT. 

15.  If  we  inquire  what  this  cause  of  short  sight  is,  we 
find  that  it  is  not  any  one  thing,  but  many  things.     Every 
thing  that  tires  and  strains  the  eyes  of  school-children, 
tends  to  make  them  short-sighted. 

Causes  of  short  sight  are,  — 

1.  Too  much  use  of  the  eyes. 

2.  Bad  light. 

3.  Wrong  positions  when  reading. 


THE  SKIN.  175 


CARE  OF  THE  EYES. 

16,  1.  If  the  eyes  are  tired  and  hot,  it  is  a  sign  that 
they  have  been  used  too  long.  Stop  until  they  are  rested. 

2.  Do  not  try  to  read  when  there  is  not  light  enough. 
If  the  light  is  dim,  the  book  will  be  held  too  near  the  eyes. 
This  tires  them,  and  causes  short  sight.  Reading  by  a 
Jading  tivilight  is  particularly  bad. 

s.  The  light  should  not  be  too  glaring.  If  it  is,  the 
nerve  is  stimulated  too  much.  This  tires  it.  Besides, 
when  any  nerve  is  over-stimulated,  it  loses  its  sensitiveness 
after  a  time;  and  then  the  book  will  be  held  too  near,  and 
short-sightedness  may  result. 

For  the  same  reason,  the  light  should,  if  possible,  fall 
over  the  left  shoulder  on  the  page.  Then  it  will  not  be 
all  reflected  into  the  eyes,  as  when  it  comes  from  in  front. 

4.  The  light  should  be  steady.     A  flickering  light  keeps 
the  eye  annoyed,  and  tires  it  with  constant  changes. 

5.  The  book  and  the  eye  should  be  steady.     It  is  as 
wearisome  to  the  eye  to  have  the  page  or  the  head  in  con- 
stant motion  as  to  have  the  light  flicker.     Heading  in  the 
cars  is  trying  to  the  eyes. 

6.  The  upright  position  is  the  natural  and  easy  one  for 
the  eyes.     To  read  when  lying  down,  or  with  the  head 
hanging  over  the  book,  tries  the  eyes,  and  tends  to  short- 
sightedness. 

7.  Any  serious  trouble  with  the  eyes  should  be  attended 
to  at  once.     It  is  better  never  to  open  a  book  than  to  lose 
the  use  of  the  eyes.     If  study  can  not  be  continued  with- 
out ruining  the  eyes,  abandon  study. 


176  THE    HUMAN    BODY. 

COLOR-BLINDNESS. 

17,  Not  a  few  people  are  color-blind.  Some  can  not 
distinguish  any  colors.  Others  can  not  recognize  a  par- 
ticular color,  as  red  or  blue,  confounding  it  with  other 
colors.  If  a  person  is  color-blind,  it  is  very  desirable  to 
know  it.  An  engineer  on  a  railroad,  who  could  not  tell  a 
red  light  from  a  green  one,  would  be  a  dangerous  person. 

EFFECTS    OF    ALCOHOL    AND    NARCOTICS. 

SECTION  V.  —  1,  A  clear  eye  and  a  good  complexion 
are  tokens  of  health.  When  the  blood  is  impure,  the 
skin  loses  its  fresh  and  delicate  appearance.  Indulgence 
in  alcoholic  drinks  flushes  the  face,  and  often  marks  it 
with  blotches  and  pimples.  Narcotics  give  a  sallow  hue 
to  the  skin. 

A  blear  eye  is  a  characteristic  mark  of  a  toper.  "  Who 
hath  redness  of  eyes  ?  They  that  tarry  long  at  the  wine." 

The  structure  of  the  eye  and  the  ear  illustrate  the 
delicacy  and  nice  adaptation  of  our  bodies.  We  are 
wonderfully  made,  and  it  is  crime  as  well  as  folly  to  blunt 
our  finer  perceptions,  and  abuse  our  various  organs,  by 
narcotics  or  alcoholic  stimulants.  We  should  rather 
cherish  and  cultivate  them  by  obedience  to  every  law 
of  health,  that  they  may  be,  as  they  were  designed  to  be, 
the  servants  and  instruments  of  our  higher  nature. 


QUESTIONS. 

SECTION  I.  —  1.  Name  some  qualities  of  the  skin. 

2,  What  is  a  blister?  Is  the  top  layer  of  the  skin  sensitive? 
Are  there  any  blood-vessels  in  the  top  layer?  Are  there  any 
nerves  or  blood-vessels  in  the  deep  layer? 


THE    SKIN.  177 


3,  What  is  dandruff?     Is  there  any  thing  similar  to  it  from  the 
surface  of  the  whole  body? 

4,  What  is  the  top  layer  of  the  skin  called?    What  is  the  deep 
layer  of  the  skin  called?     What  are  the  papillae,  and  where  are 
they  situated  ? 

5,  What  makes  the  ridges  and  furrows  on  the  skin  of  the  palm? 

6,  What  are  the  pores?     Describe   a  sweat-duct.     Describe  a 
sweat-gland.    Where  does  the  sweat  come  from?    How  does  it  get 
into  the  duct?    What  is  the  estimated  number  of  pores?    What  is 
the  estimated  length  of  all  the  ducts  combined? 

7,  What  is  insensible  perspiration?    What  is  sensible  perspira- 
tion? 

8,  What  is  the  use  of  the  hair?    What  does  it  grow  from?    How 
do  the  muscular  fibers  of  the  skin  act  on  the  hairs? 

9,  Where  are  the  sebaceous  glands,  and  what  do  they  do? 

10,  What  is  the  use  of  the  nails?    What  do  they  grow  from? 
What  is  the  root  of  the  nail?    What  is  the  matrix  of  the  nail? 
When  a  nail  comes  off,  is  it  ever  restored?    When  is  it  not  restored? 

11,  Name  three  uses  of  the  skin. 

12,  What  is  the  natural  heat  of  the  inside  of  the  body? 

13,  How  is  it  kept  just  at  this  temperature? 

14,  What  makes  heat  in  the  body? 

15,  How  is  the  temperature  of  the  different  parts  kept  equal? 

16,  How  do  clothes  keep  the  body  warm?    In  what  two  ways  are 
we  helped  to  resist  the  cold? 

17,  Describe  the  first-named  method  in  which  the  skin  acts  as  a 
cooling-apparatus.     Describe  the  second-named  method  in  which 
the  skin  acts  as  a  cooling-apparatus.     How  can  men  endure  a  tem- 
perature of  200°  F.? 

SECTION  II.  —  1.  What  shows  the  importance  of  the  action  of 
the  skin? 

2-6.  What  three  things  are  necessary  in  order  to  keep  the  skin 
healthy?  How  does  the  skin  become  clogged  and  over-sensitive? 
How  may  we  become  liable  to  colds?  What  is  the  harm,  of  too 
thick  clothing?  What  are  the  advantages  of  rubbing  the  skin? 

7-10,  WTiat  is  the  use  of  bathing?  Why  is  cold-water  bathing 
invigorating?  What  is  the  best  safeguard  against  colds?  What 
cautions  are  to  be  observed  in  bathing? 


178  THE   HUMAN    BODY. 

SECTION  III.  —  I,  Name  the  three  divisions  of  the  ear. 

2,  What  is  the  use  of  the  external  ear?    What  is  it  made  of? 

3,  Describe  the  external  auditory  canal. 

4,  What  is  the  drum-head?    What  is  the  drum?    Is  there  any 
opening  out  of  the  drum  ? 

5,  Where  is  the  internal  ear?    What  is  its  importance? 

6,  What  is  sound  ? 

7,  What  is  the  position  of  the  little  bones  in  the  ear? 

8,  What  is  the  use  of  the  little  bones?    How  does  the  vibration 
reach  the  nerve  of  hearing? 

9,  Does  the  ear  hear? 

10,  What  frequently  causes  an  ear-ache?    From  what  spot  does  a 
discharge  from  the  ear  commonly  come?    Is  a  broken  drum-head 
ever  repaired  ? 

11,  Does  the  loss  of  the  drum-head  destroy  hearing? 

12,  What  is  ear-wax?    Is  it  safe  to  put  instruments  in  the  ear? 

SECTION  IV.  —  1.  Describe  the  orbits. 

2,  State  the  shape,  size,  and  position  of  the  eyeball. 

3,  What  is  the  sclerotic  coat  of  the  eye?    What  is  the  cornea? 

4,  What  divides  the  eye  into  two  chambers?    What  fills  the  pos- 
terior chamber?    The  anterior  chamber?     What  is  the  retina? 

5,  Describe  the  iris.     The  pupil.    What  is  the  action  of  the  iris? 

6,  What  is  the  conjunctiva?    What  is  the  use  of  the  eyelashes? 
What  are  the  Meibomian  glands?  and  what  is  their  use?    Where  is 
the  lachrymal  gland?     What  is  its  use? 

7,  What  are  tears?     How  are  they  carried  off  from  the  eye? 

8,  What  muscles  move  the  eyeball?  and  how  do  they  act? 

9,  How  does  the  eye  resemble  a  photographer's  camera? 

10,  Where  is  a  picture  of  the  object  looked  at  formed? 

11-17,  Name  some  causes  of  trouble  in  the  eye.  ^  What  is  the 
effect  of  too  long  sight?  What  is  the  remedy?  What  is  the  effect 
of  too  short  sight?  Among  what  class  is  it  most  common?  What 
are  causes  of  too  short  sight?  Give  rules  for  the  care  of  the  eyes. 
What  is  color-blindness  ? 

SECTION  V.  —  1.  What  are  the  effects  of  alcohol  and  narcotics  on 
the  skin  and  eyes? 


APPENDIX 


APPENDIX. 


\VHAT   TO    DO    IN    CASE    OF   ACCIDENT. 

IT  is  natural  to  be  alarmed  when  an  accident  occurs.  Our 
feelings  of  sympathy  for  the  sufferer,  and  perhaps  of  fear 
that  he  will  die,  agitate  us,  and  scatter  our  wits,  and  make  us 
helpless.  The  first  thing  at  such  a  time,  is  to  think.  "  What 
can  I  do  ?  "  is  the  question.  To  apply  the  mind  vigorously 
to  that  question,  is  the  best  way  to  control  the  feelings. 

We  can  not  anticipate  all  the  particulars  of  accidents  that 
may  happen,  but  we  can  fix  in  the  mind  a  few  simple  direc- 
tions for  each  kind. 

Painting.  —  When  a  person  faints,  the  heart  almost  stops 
beating.  The  face  is  deadly  pale.  If  we  could  see  the  brain, 
we  should  see  that  pale  too.  Because  the  blood  is  not  sent  to 
it  in  sufficient  amount,  it  partly  stops  acting,  and  the  person 
is  unconscious. 

Place  him  on  his  back,  with  his  head  low.  The  blood  will 
flow  to  the  brain  more  easily  in  the  horizontal  than  in  the 
upright  position. 

Give  him  air.  Perhaps  he  has  fainted  because  the  air  is 
bad.  Fresh  air  will  revive  him. 

Sprinkle  cold  water  on  the  face.  It  stimulates  and  rouses 
the  nerves. 

181 


182  APPENDIX. 


Loosen  the  clothing  about  the  neck  and  waist,  so  that  it  may 
be  easy  to  breathe. 

A  fainting-fit  generally  lasts  only  a  short  time. 

Pits.  — In  fainting,  the  face  is  pale,  the  pulse  can  hardly  be 
felt,  the  limbs  are  limp  and  still.  In  fits,  the  face  may  be  pale 
or  red,  the  pulse  can  be  felt  easily,  and  the  limbs  often  jerk 
and  draw  up  spasmodically.  Frothing  at  the  mouth  is  not 
uncommon.  If  the  fit  is  a  long  one,  or  if  several  come  in 
succession,  there  will  be  time  for  the  doctor  to  arrive.  What 
you  can  do,  is, — 

2.  To  keep  the  person  from  hurting  himself  in  his  struggles. 

2.  To  give  him  plenty  of  air. 

3  To  see  that  there  is  nothing  tight  around  his  neck  or  chest. 

4.  Place  him  with  his  head  raised  a  little. 

5.  When  he  comes  out  of  the  fit,  let  him  rest. 

Sunstroke. — This  happens  to  those  who  have  been  ex- 
posed to  great  heat,  either  in  the  sunshine  or  in  the  shade. 
The  face  is  flushed  or  pale,  the  pulse  quick,  and  the  skin  dry 
and  hot. 

Put  the  sufferer  in  as  cool  a  place  as  possible,  with  his  head 
raised,  and  apply  cold  water  or  ice  to  his  head  and  chest.  If 
he  seems  extremely  weak,  and  the  skin  becomes  cool,  stop 
using  ice,  and  put  mustard  and  water  on  his  feet  and  on  the 
back  of  his  neck. 

Shock. — Shock  is  the  name  given  to  the  condition  of  pros- 
tration which  sometimes  follows  a  severe  injury.  The  person 
is  conscious,  but  extremely  weak.  The  face  is  pale,  the  skin 
cool,  and  perhaps  moist,  the  pulse  quick  and  small,  and  there 
is  restlessness.  The  powers  may  continue  to  fail  until  death 
comes.  More  frequently  they  rally  after  a  time. 

A  person  in  this  condition  must  be  handled  very  carefully. 
Any  roughness  may  quench  the  spark  of  life.  He  must  be 
laid  down  with  his  head  low.  Nature  must  be  aided  by 


APPENDIX.  183 


gentle  stimulants.  Heat  is  one  of  the  best  stimulants.  Put 
hot-water  bottles  at  his  feet  and  sides.  Give  air,  but  avoid 
chilling  him.  Do  not  move  him  until  he  is  better. 

Fractures  and  Dislocations.  —  A  broken  or  dislocated 
limb  is  generally  helpless.  Even  when  there  is  no  pain  in 
it,  it  can  not  be  used.  If  there  is  reason  for  thinking  that 
such  an  accident  has  happened,  the  limb  should  be  seen 
immediately  by  a  doctor.  In  the  mean  time  keep  it  per- 
fectly quiet.  Do  not  allow  the  patient  to  attempt  to  use  it. 
Support  it  in  the  position  in  which  it  is  most  comfortable. 
Bathe  it  in  cold  or  hot  water  to  relieve  pain  and  keep  down 
swelling. 

Bleeding. — When  blood  is  flowing  from  a  wound,  it  must 
be  stopped.  In  most  cases  it  is  only  necessary  to  press  a 
handkerchief  on  it.  This  will  check  the  flow  so  that  the 
blood  can  coagulate  in  the  vessels.  Sometimes  it  is  neces- 
sary to  press  hard  upon  the  wound  for  a  good  while.  Some- 
times this  will  not  be  sufficient.  The  blood  is  flowing,  perhaps, 
from  a  large  artery.  Then  a  bandage  must  be  drawn  tight 
around  the  limb  above  the  wound.  If  the  bleeding  stops,  the 
bandage  may  be  taken  off  in  half  an  hour.  If  the  bleeding 
does  not  stop,  it  is,  perhaps,  coming  from  a  vein ;  and  a  band- 
age must  be  tied  around  the  limb  below  the  wound.  It  may 
be  necessary  to  find  the  course  of  the  bleeding  vessel,  and  press 
on  it  with  the  thumb.  In  some  of  these  ways,  external  bleed- 
ing can  always  be  checked  for  the  time. 

Bleeding  from  the  Nose.  —  Let  the  person  keep  upright,  and 
hold  his  hands  above  his  head.  Apply  cold  to  the  back  of 
the  neck  and  to  the  forehead.  Press  on  the- nostrils.  Push  a 
little  wad  of  cotton  into  the  nostrils. 

Bleeding  from  the  Langs  or  Stomach  or  Bowels.  —  Keep  the 
patient  perfectly  quiet  on  his  back.  Do  not  let  him  talk. 
Give  him  ice  to  swallow,  and  salt  and  water. 


184  APPENDIX. 


Poisoning.  —  If  the  poison  has  not  been  in  the  stomach 
more  than  an  hour  or  two,  try  to  make  the  patient  vomit. 
This  can  sometimes  be  done  by  tickling  the  throat  with  the 
finger  or  a  feather.  If  this  is  not  sufficient,  give  a  teaspoonful 
of  mustard  in  a  tumbler  of  lukewarm  water.  Or  give  a 
dose  of  ipecac.  If  the  poison  is  causing  pain  in  the  stomach, 
give  the  whites  of  two  or  three  eggs.  If  the  poison  is  an  acid 
(as  sulphuric  acid),  give  soapsuds  or  magnesia.  If  the  poison 
is  a  narcotic,  like  opium  or  belladonna  or  chloral,  keep  the 
person  from  going  to  sleep. 

Drowning. — When  a  person,  apparently  drowned,  is  taken 
out  of  the  water,  his  lungs  have  water  in  them,  and  his  throat 
is  stopped  with  water  and  mucus.  Turn  him  on  his  face,  and 
let  the  water  run  out  of  his  mouth.  Thrust  your  finger  in 
his  mouth,  and  clear  it,  and  draw  his  tongue  forward.  Then 
lay  him  on  his  back,  with  a  folded  coat  under  his  shoulders, 
raising  them  a  little  higher  than  his  head.  Tickle  his  nostrils 
with  a  feather.  Give  a  little  snuff,  or  a  smell  of  smelling- 
salts.  This  may  start  his  breathing.  If  it  does  not,  try  to 
make  his  chest  expand  and  contract  as  it  does  naturally.  A 
good  way  to  do  this  is  to  stand  across  his  body,  or  above  his 
head,  take  hold  of  his  arms,  and  bring  his  elbows  up  to  the 
sides  of  his  head.  This  opens  the  chest  and  lungs,  and  imi- 
tates the  movement  of  inspiration.  Then  bring  his  arms 
down  to  his  sides,  and  press  them  against  the  walls  of  the 
chest.  This  contracts  the  chest  and  lungs,  and  imitates  the 
movement  of  expiration.  Do  this  fifteen  or  twenty  times  in 
a  minute  for  half  an  hour,  if  the  chest  does  not  begin  to  open 
and  contract  of  itself  in  less  time.  At  the  same  time,  let 
others  get  off  the  wet  clothing,  and  cover  with  dry.  Let  them 
rub  the  limbs  vigorously,  rubbing  from  the  extremity  toward 
the  center.  If  bottles  of  hot  water,  or  hot  bricks  or  hot  flan- 
nels, can  be  had,  put  them  at  his  feet  and  sides.  The  three 
things  to  be  aimed  at,  are, — 


APPENDIX.  185 


1.  To  start  the  movements  of  breathing. 

2.  To  restore  warmth. 

3.  To  quicken  the  current  of  blood. 

Persevering  and  energetic  efforts  will  often  be  rewarded  by 
a  return  of  the  signs  of  life  when  they  seemed  to  have  gone 
forever. 

Remember  that  "  a  little  knowledge  is  a-  dangerous  thing  " 
if  it  leads  to  undue  self-confidence.  In  case  of  serious  ac- 
cident, never  fail  to  get  help  if  possible  from  some  one  more 
experienced  and  capable  than  yourself. 


GLOSSARY. 


GLOSSARY. 


Ab-do'men.    The  belly. 

Ad'am's  ap-ple.  A  prominence  in 
the  middle  line  of  the  neck. 

A-dul'ter-ate.  To  make  impure  by 
adding  inferior  substances. 

Al'i-ment.    Nourishment. 

Al-i-me'nt'a-ry.  Pertaining  to  ali- 
ment. 

A-nat'o-my.  The  science  of  the 
structure  of  organized  bodies. 

A-or'ta.  The  great  artery  which 
comes  from  the  heart,  and  passes 
down  by  the  backbone. 

Ap-o-neu-ro'sis.  A  membrane  of 
white  fibrous  tissue  connected  with 
a  muscle. 

Ap'o-plex-y.  A  disease  of  the  brain 
in  which  sense,  and  power  of  mo- 
tion, are  suddenly  lost. 

A'que-ous.  Watery.  A  term  ap- 
plied to  the  fluid  contents  of  the 
anterior  chamber  of  the  eyeball. 

Ath'lete  (Lat.,  athleta,  one  who  con- 
tends for  a  prize).  One  who  espe- 
cially cultivates  his  muscles, 

Au'di-to-ry  (Lai.,  aridities,  hearing). 
Pertaining  to  the  hearing. 

Au'ri-cle  (Lat.,  auricula,  a  little  ear). 
A  name  given  to  two  of  the  cavities 
of  the  heart. 

Ax-Il'la.    The  arm-pit. 

Bi'ceps  (Lat.,  bis,caput,  two-headed) 
A  muscle  extending  from  the  shoul- 
der to  the  fore-arm,  on  the  front  of 


the  arm.  Also,  a  muscle  extend- 
ing from  the  hip  to  the  leg,  on  the 
back  of  the  thigh. 

Brach'i-al  (Lat.,  brachium,  the  arm). 
Pertaining  to  the  arm. 

Bun'ion.  An  enlargement  and  in- 
flammation at  the  first  joint  of  the 
great  toe. 

Cap'il-la-ry  (Lat.,  capillus,  hair). 
Hairlike 

Ca-rot'id.  A  name  applied  to  sev- 
eral arteries  in  the  neck, 

Car'pus.    The  wrist 

Car'ti-lage.    Gristle 

Ca-tarrh'.  An  inflammation  of  the 
mucous  membrane. 

Cau'da  e-quT-na  (horse's  tail).  The 
bundle  of  nerves  into  which  the 
spinal  cord  divides  at  its  lower  end. 

Cer-e-bel'lum.  A  division  of  the 
brain,  behind  and  beneath  the  cere- 
brum 

Cer'e-brum.  The  largest  division 
of  the  brain. 

Chyle.  The  emulsion  of  fats  made 
in  the  intestine. 

Chyme.  The  gruel-like  mixture 
which  passes  from  the  stomach 
into  the  intestine  in  digestion. 

Clav'i-cle.    The  collar-bone. 

Co-ag-u-la'tioii.  The  forming  of 
clots 

Coc'cyx  (Lat.,  coccyx,  a  cuckoo).  A 
bone  at  the  lower  end  of  the 
189 


190 


GLOSSARY. 


backbone,  shaped  like  a  cuckoo's 
beak. 

Con-junc-ti'va.  The  mucous  mem- 
brane covering  the  front  of  the  eye- 
ball, and  lining  the  lids. 

C6n-vo-lu'tioiis.  Ridges  on  the 
surface  of  the  cerebrum  and  cere- 
bellum. 

Corn  (Lat.,  cornu,  a  horn).  A  small 
portion  of  the  epidermis,  of  horn- 
like hardness. 

Cor'ne-a  (Lat.,  cornea,  horny).  The 
circular,  transparent  membrane  in 
the  front  of  the  eye. 

Cor'pus-cle  (Lat.,  corpusMilumt  a 
small  body).  A  minute  particle 

Cos'tal  (Lat.,  costa,  a  rib).  Pertain- 
ing to  the  ribs. 

Cu'ti-cle.  The  upper  layer  of  the 
skin. 

Cu'tis  ve'ra  (true  skin).  The  deep 
layer  of  the  skin. 

Dan'druff.  A  scurf  which  forms 
on  the  scalp,  and  comes  off  in 
small  scales. 

Dgn'tine  (Lat.,  dens,  a  tooth).  A 
bonelike  substance  of  which  the 
teeth  are  made. 

Der'ma.  The  deep  layer  of  the 
skin. 

Di'a-phragm  'midriff)  A  sheet 
made  of  muscle  and  fibrous  mem- 
brane between  the  chest  and  ab- 
domen. 

Duct.  A  tube  by  which  a  fluid,  or 
other  substance,  is  conducted. 

Dys-p6p'si-a.    Bad  digestion. 

El'e-ment.  One  of  the  simplest 
parts  of  which  any  thing  consists. 
A  name  applied  to  those  simple 
substances,  between  sixty  and  sev- 
enty in  number,  to  some  of  which 
all  material  objects  can  be  re- 
duced. 

E-inul'sion.    A  mixture  of  oil  with 


water  containing  some  gummy  or 
albuminous  substance. 

En-am'el.  The  hard  and  polished 
substance  which  covers  the  crown 
of  a  tooth. 

Ep-i-derm'is.  The  upper  layer  of 
the  skin. 

Eu-sta'chi-an  tube.  A  tube  con- 
necting the  middle  ear  with  the 
throat. 

Ex-pi'ra-to-ry  (Lat.,  ex  spirare,  to 
breathe  out).  Out-breathing. 

Fem'o-ral.    Pertaining  to  the  thigh. 

Fe'mur.    The  thigh-bone. 

Fi'ber.    A  thread  of  tissue. 

Fi-bro-car'ti-lage.  A  tissue  made 
of  cartilage,  with  white  fibers 
mixed  with  it. 

Fi'brous  me'm'brane.  A  mem- 
brane made  of  fibers. 

Fib'u-la.  A  slender  bone  in  the 
calf  of  the  leg 

Fla'vor.  That  which  gives  a  pe- 
culiar odor  or  taste. 

Fos'sa  (Lat.,/ossa,  a  ditch).  A  de- 
pression in  a  bone. 

Gas'tric.  Pertaining  to  the  stom- 
ach. 

Gas-troc-ne'mi-us.  The  large  mus- 
cle extending  from  the  thigh  to  the 
heel  on  the  calf  of  the  leg. 

Gland.  A  name  applied  to  many 
organs  which  take  part  in  the  pro- 
cesses of  life. 

Glob'ule.    A  little  globe. 

Glot'tis.  A  slit  in  the  membranous 
partition  between  the  upper  and 
lower  parts  of  the  larynx. 

Glu'ten.  A  substance  in  grain  that 
contains  the  same  chemical  ele- 
ments that  meat  contains. 

Gly'co-gen.  A  substance  formed  in 
the  body  chiefly  by  the  liver. 

Ha-ver'sian  ca-nals'  (from  Havers, 
who  first  described  them).  Micro- 


GLOSSARY. 


191 


scopic  canals  in  bone,  in  which  the 
blood-vessels  run. 

Hu'me-rus.    The  arm-bone. 

Hy'gi-ene.    The  science  of  health. 

Hy'oid.    U-shaped. 

In-spi'ra-to-ry  (Lat.  In  spirare^  to 
breathe  in).  In-breathing. 

I'ris  (Lat.,  iris,  the  rainbow).  A 
colored  muscular  membrane  in  the 
anterior  chamber  of  the  eye. 

Jaun'dlce.  A  disease  in  which  the 
body  is  colored  yellow. 

Ju'gu-lar  (Lat.,Jt(/]rufam,  the  neck). 
Pertaining  to  the  neck. 

Lach'ry-mal  (Lat.,  lawyma,  a  tear). 
Pertaining  to  tears, 

Lac'te-al  (Lat,,  lac,  milk).  A  term 
applied  to  the  lymphatic  ducts  of 
the  intestine. 

Lig'a-ment  (Lat.,  lie/are,  to  bind), 
A  fibrous  band  that  binds  two  parts 
(commonly  bones)  together. 

Lymph.  The  contents  of  the  lym- 
phatic vessels. 

Mar'rSw.  A  soft  substance  con- 
tained in  the  cavities  of  bone. 

Ma'trix.  An  organ  which  produces 
or  gives  form  to  any  thing, 

Me-dul'la  ob-loii-ga'ta.  The  low- 
est division  of  the  brain. 

Mei-bo'mi-an.  Discovered  or  de- 
scribed by  Meibomius. 

Met-a-car'pus.  The  part  of  the 
hand  between  the  wrist  and  the 
fingers. 

Met-a-tar'sus.    The  flat  of  the  foot. 

Mi'tral.  Like  a  miter,  or  bishop's 
cap. 

Mu'cous  mem'brane.  A  mem- 
brane lining  all  the  cavities  of  the 
body  that  are  connected  with  the 
outer  world. 

Mu'cus.  The  fluid  which  comes 
from  the  surface  of  the  mucous 
membrane. 


Nar-cot'ic.  That  which  benumbs 
and  stupefies. 

Na'sal.    Pertaining  to  the  nose. 

Nau'se-a.    Sickness  at  the  stomach 

Nu'cle-us.  In  anatomy,  a  cell  with- 
in a  cell 

GE-soph'a-gus.    The  gullet. 

Orb'it.  The  bony  cavity  in  which 
the  eye  is  situated. 

Os  in-ndm-i-ua'tum  (nameless 
bone).  The  hip-l>one. 

Pal-pi-ta'tion.  A  hard,  rapid  beat- 
ing of  the  heart. 

Pan'cre-as.  An  organ  of  digestion. 
The  sweet-bread  in  calves. 

Pa-pll'la.  A  conelike  prominence 
of  the  skin  or  mucous  membrane. 

Par'a-sfte.  A  plant  or  animal  that 
grows  or  lives  on  another. 

Pa-rot'id.  The  name  of  a  large 
gland  under  the  ear. 

Pa-tel'la.    The  knee-pan. 

Pec'to-ral  (Lat.,  pectus,  the  breast). 
Pertaining  to  the  breast. 

PeTvis  (Lat.,  a  basin).  The  cavity 
inclosed  by  the  hip-bones  and  the 
lower  end  of  the  backbone. 

Pep'sin.  The  active  principle  of  the 
gastric  juice. 

Per-i-car'di-um.  A  membranous 
bag  inclosing  the  heart. 

Per-i-6s'te-um.  The  membrane 
which  covers  bones. 

Pha'lanx.  One  of  the  small  bones 
of  the  fingers  and  toes. 

Phar'ynx.    The  throat. 

Phys-i-ol'o-gy.  The  science  of  the 
functions  of  organized  bodies. 

Plas'ma.  The  watery  part  of  the 
blood. 

Pleu'ra.  A  sac  which  covers  the 
lung. 

Pons  Va-ro'lii  (bridge  of  Varolius). 
A  division  of  the  brain  which  con- 
nects the  other  main  divisions. 


192 


GLOSSARY. 


P5re.    The  outlet  of  a  sweat-duct. 

Proc'ess.  A  bony  projection  from 
a  bone. 

PfiFmo-na-ry  (Lat.,  pulmo,  a  lung). 
Pertaining  to  the  lungs. 

Pti'pil.  The  central  opening  in  the 
iris 

Py-lo'rus.  A  muscular  ring  which 
surrounds  the  outlet  of  the  stom- 
ach. 

Ra'di-al.  Pertaining  to  the  ra- 
dius. 

Ra'di-us.  The  outer  bone  of  the 
fore-arm. 

Re's-pi-ra/tion.  The  process  by 
which  oxygen  is  introduced  into 
the  blood,  and  carbonic-acid  gas 
and  vapor,  and  other  matters,  are 
discharged  from  it. 

Ret'i-na  (Lat.,  rete,  a  net).  The  ter- 
minal fibers  of  the  optic  nerve  lin- 
ing the  back  part  of  the  eye. 

Sa'crum.    A  part  of  the  backbone. 

Sa-H'va.    Spittle. 

Sar-t5'ri-us.  A  muscle  extending 
from  the  hip  to  the  leg,  on  the 
front  of  the  thigh. 

Scap'u-la.    The  shoulder-blade. 

Scle-rot'ic  (Lat.,  scleroticus,  hard, 
firm).  A  term  applied  to  the  outer 
coat  of  the  eye. 

Se-ba'ceous  (Lat.,  sebaceus,  tallowy). 
Applied  to  glands  in  the  skin  that 
produce  a  fatty  fluid. 

Sem-i-lu'nar.  Shaped  like  a  half- 
moon. 

Sew'age.    The  contents  of  sewers. 

SkeTe-ton.  The  framework  of  an 
organized  body,  of  bone  or  other 
firm  material. 

Skull.  The  bony  frame  of  the 
head. 

Spi'nal  ca-naT.  The  canal  in  the 
center  of  the  backbone. 

Spl'nal  col'umn.    The  backbone. 


Spi'nal  cord.  A  cord  of  nerve- 
matter  in  the  spinal  canal. 

Sprain.  An  injury  to  the  ligaments 
or  tendons  about  a  joint. 

Sta-pe'di-us.  A  very  small  muscle 
in  the  drum  of  the  ear. 

Ster'num.    The  breast-bone. 

StTm'ii-lant  (Lat.,  stimulus,  a  goad). 
That  which  goads  or  excites. 

Sub-cla'vi-an.  Beneath  the  clavicle. 

Sub-lm'gual  (Lat.,  sub  lingua,  un- 
der the  tongue).  The  name  of  a 
salivary  gland. 

Sub-mSx'il-la-ry  (Lat.,  sub  maxilla, 
under  the  jaw).  The  name  of  a 
salivary  gland. 

Syii-o'vi-a.    Joint-water. 

Syn-o'vi-al  mem'brane.  A  thin 
membrane  which  lines  the  joint- 
cavity,  and  gives  out  the  joint- 
water. 

Sys-tem'ic.  Pertaining  to  the  gen- 
eral system. 

Tape'worm.  A  worm  that  lives  in 
the  alimentary  canal. 

Tar'sus.  A  portion  of  the  foot  be- 
tween the  leg  and  the  metatarsus. 

Ten'don.  A  cord  of  white,  fibrous 
tissue  connected  with  a  muscle. 

Ten'don  of  A-chil'les.  The  ten- 
don of  the  gastrocnemius  and  so- 
leus  muscles  inserted  in  the  heel. 
It  was  fabled  that  this  was  the  only 
part  in  which  Achilles  was  vul- 
nerable. 

Tho'rax.    The  chest. 

TIb'i-a.    The  shin-bone. 

Tib'i-al.    Pertaining  to  the  tibia. 

Trans-fu'sion  (Lat.,  trans,  across, 
fundere,  to  pour).  Pouring  blood 
from  the  veins  of  one  person  into 
those  of  another. 

Tri-chi'na.  A  small  worm  that 
lives  in  the  muscles  of  pigs,  and  of 
some  other  animals,  and  of  men. 


GLOSSARY. 


193 


Tri-chi-no'sis.  The  disease  caused 
by  trichinae  in  the  body. 

Tri-ciis'pid.    Three-pointed, 

Tym'pa-num  (a  drum).  The  middle 
ear. 

Ul'na.  The  inner  bone  of  the  fore- 
arm. 

Ul'nar.    Pertaining  to  the  ulna. 

Ven'tri-cle  (Lat.,  ventriculus,  the 
belly)  A  name  given  to  several 
small  cavities  in  the  body. 


Ver'te-bra  (Lat.,  vertere,  to  turn). 
One  of  the  bones  which  make  the 
backbone. 

Vil'lus.  A  hairlike  projection  from 
the  lining  of  the  intestine. 

Vit/re-ous  (Lat.,  vitreus,  glassy).  A 
term  applied  to  the  semi-fluid  con- 
tents of  the  posterior  chamber  of 
the  eyeball. 

Vo'cal  cords.  Two  fibrous  bands 
that  form  the  margins  of  the  glottis. 


INDEX. 


INDEX. 


ABDOMEN,  18, 132. 
Absorption,  110. 
Abstinence,  48. 
Acidity,  115. 
Adam's  apple,  23,  130. 
Adulteration,  93. 
Air,  47,  52,  121,  122. 
"    bad,  151. 
"    polluted,  136. 
Air-cells,  130. 
Air-passages,  127. 
Alcohol,  48,  55,  73,  88,  92,  116,  151. 

"       affinity  for  the  brain,  153. 
after-effects  of,  152. 

"        how  made,  92. 

"        an  irritant,  116. 

"        effects  on  the  appetite,  56. 

"        effects  on  the  arteries,  74. 

"        effects  on  the  bones,  34. 

"        effects  on  the  brain,  153. 

"        effects  on  the  breath,  139. 

"        effects  on  the  circulation,  73. 

"        effects  on  digestion,  116. 

"        effects  on  the  gastric  juice, 
117. 

"        effects  on  the  heart,  65,  74. 

"        effects  on  the  intestine,  117. 

"        effects  on  the  kidneys,  118. 

"        effects  on  the  liver,  118. 

"        effects  on  the  nervous  sys- 
tem, 151-153. 
Ale,  93. 

Alertness,  45,  46. 
Alimentary  canal,  98. 

"  "        divisions  of,   100, 

110. 
Anatomy,  definition  of,  13,  14. 


Ankle,  27,  31. 
Aorta,  60,  64,  68. 
Aponeurosis,  41. 
Apoplexy,  74. 
Appetite,  87. 
Aqueduct-pipes,  87. 
Aqueous  humor,  170. 
Arm,  23. 

Armies,  feeding,  81. 
Arteries,  60,  61. 

"        carotid,  69. 
"         differ  from  veins,  70. 
"        flow  of  blood  in,  69. 
"        strength  of,  71. 
"        walls  of,  72. 
Artery,  axillary,  69. 
"        brachial,  69. 
"        femoral,  69. 
"        pulmonary,  63,  71. 
"        radial,  69. 
"        subclavian,  69. 
"        tibial,  69. 
"        ulnar,  69. 
Athletes,  46,  48,  94. 
Auricles,  62. 
Auricle,  right,  63. 
left,  64. 

BACKBONE,  19,  22,  53. 

"  injury  of,  143. 

Bathing,  166. 

"        cautions,  167. 
Beans,  81. 
Beer,  93. 
Beets,  82. 

Beaumont,  Dr.,  116. 
Beef,  79. 

197 


198 


INDEX. 


Bicuspids,  103. 

Bile,  108,  109. 

Birds,  blood-corpuscles  of,  53. 

Black  Hole,  137. 

Bleeding,  183. 

Blister,  156. 

Blood,  52. 

"      a  carrier,  110, 135. 

"      impure,  55. 

"      amount  of,  55. 

"      loss  of,  55. 

"      color  of,  54. 

"      in  murder-trials,  53. 

"      changes  in  color,  134. 
Blood-vessels,  60. 

"  variations  in  size  of,  72. 

"  enlargement  of,  153. 

Blush,  73. 
Bone,  blood-vessels  of,  29. 

"     chemical  composition  of,  30. 

"     nerves  of,  29. 

"     structure  of,  28. 
Bones,  number  of,  19. 
Bowels,  98. 
Bow-legs,  30. 
Brain,  17. 

"      convolutions  of,  144. 

"      exercise  of,  151. 

"      injury  of,  143. 

"      gray  matter  of,  145. 

"      white  matter  of,  145. 
Brandy,  93. 
Bread,  83,  84. 
Breast-bone,  18,  22. 
Breath,  amount  of,  136. 
"       changes  in,  136. 
"       contents  of,  135. 
Breathing,  involuntary,  133. 

process  of,  131, 133. 
Bright's  disease,  118. 
Bronchi,  structure  of,  130. 
Bronchial  tubes,  130. 
Bunion,  28. 
Butter,  82,  101. 
Buttermilk,  83. 


CABBAGES,  82. 
Cake,  83,  84,  85. 
Camera,  172. 
Canines,  103. 
Capillaries,  60,  61,  64. 

"  flow  of  blood  in,  67. 

"          walls  of,  70. 
Carbon,  78. 

Carbonic-acid  gas,  122, 123, 134. 
Care  of  the  eyes,  175. 
Carpus,  24. 
Cartilage,  22,  32. 
Catarrh,  166. 
Cauda  equina,  145. 
Cavity  of  the  skull,  17. 

"      of  the  spinal  column,  17. 

"      of  the  trunk,  18. 
Cerebrum,  143,  150. 
Cerebellum,  143. 
Chest,  131. 

Chinese  mode  of  making  tea,  89. 
Chloral,  94. 
Chyle,  101,  111. 

"      absorption  of,  112. 
Chyme,  111. 

"       absorption  of,  112. 
Cider,  93,  94. 

Circulation,  organs  of,  60. 
Clavicle,  23. 
Close  rooms,  151. 
Clothing,  163. 
Coagulation,  54. 
Coccyx,  18,  19,  20. 
Coffee,  89. 
Colds,  129, 165,  166. 
Color-blindness,  176 
Collar-bones,  23. 
Conjunctiva,  171. 
Convolutions,  144. 
Cookery,  85. 
Cooking,  83. 
Cornea,  170. 
Corn,  81. 

"      on  the  foot,  28. 
Corpuscles,  red,  53. 


INDEX. 


199 


Corpuscles,  white,  53.  54. 
Costal  cartilages,  22. 
Coughing,  149. 
Crabs.  80. 
Cream,  83,  101. 
Curves  of  the  spine,  21. 
Cuticle,  157. 
Cutis  vera,  157. 

DANDRUFF,  156. 
Dentine,  104, 
Derma,  157. 
Diaphragm,  61, 131. 
Diet,  ordinary,  79. 
Digestion,  100 

first  act  in,  104. 
"         hinderances  to,  115. 
Digestive  juices,  101. 
Dislocations,  183. 
Dissipation,  65. 
Drainage,  86. 
Drinkers,  152. 

"         stomachs  of,  117. 
Drowning,  184. 
Drowsiness,  51. 
Duct,  nasal,  172. 

"      right  lymphatic,  112. 

"      thoracic,  112. 
Ducts,  106. 

"       of  sweat-glands,  158. 
Dyspepsia,  102. 

EAR,  167. 

"     bones  of,  168. 

"      drum  of,  168. 
Earache,  169. 
Ear-wax,  169. 
Eating-habits,  87. 
Eating  too  fast,  115. 

"       irregularity  in,  116. 
Eggs,  80. 
Elbow,  31. 
Elements,  77. 
Elephant,  53. 
Emulsion,  101, 109. 


Enamel  of  the  teeth,  50,  104. 
Endurance,  45,  46. 
Epidermis,  157. 
Epilepsy,  153. 
Eustachian  tul>e,  168. 
Evaporation,  164. 
Excitement,  66, 151. 
Excess  in  exercise,  47. 
Exercise  for  men,  46. 

"         for  women,  46. 

"         lack  of,  116,  151 
law  of,  44. 

"         regular,  46. 
Expression,  47. 
Expiratory  muscles,  132. 
Eye,  170. 
"    care  of,  175. 
"    trouble  in,  173. 
Eyeball,  170. 
Eyelashes,  171. 

FAINTING,  55,  181. 

F'armers,  44. 

Fat,  82,  101. 

Fatigue,  51,115. 

Femur,  26. 

Fermentation,  93. 

Fibers,  43 

Fibro-cartilage,  20. 

Fibula,  26. 

Fingers,  24. 

Fish,  80. 

Fishes,  breathing  of,  125. 

Fits,  182. 

Flavors,  83. 

Flesh,  40. 

Food,  52,  77,  98. 

"     daily  amount  of,  88. 

"     fried  in  fat,  84. 

"      indigestible,  151. 

"      too  much,  115. 
Foot,  25. 

"     abuse  of,  28. 

"     divisions  of,  27. 
Fore-arm,  23,  24. 


200 


INDEX. 


Fractures,  183. 

Frogs,  breathing  of,  124. 

Funny-bone,  145, 146. 

GAME,  79. 

Gastric  juice,  106. 

Germs  of  disease,  86. 

Gills,  125. 

Gin,  93. 

Gin-drinkers'  liver,  118. 

Glands,  100. 

"       digestive,  110. 

"       parotid,  105. 

"       salivary,  105. 

"       sebaceous,  160. 

"       subling-ual,  105. 

•'       submaxillary,  105. 
Glasses,  174. 
Glottis,  138. 
Gluten,  SO. 
Glycogen,  108. 
Goose-flesh,  160. 
Graham  flour,  81. 
Grasses,  78. 

Greater  circulation,  66. 
Greeks,  45. 
Gullet,  100. 

HABITS,  151. 
Hair,  159. 
Hand,  23,  24,  25. 
Harvey,  William,  70. 
Haversian  canals,  29. 
Head,  injury  of,  143. 

"      number  of  bones  in,  19. 
Hearing,  organs  of,  19. 
Heat,  bodily,  161,  162. 
Heart,  (51,73. 

Heart-beats  in  a  minute,  65. 
Heart,  contractions  of,  64,  66,  67. 

"      endurance  of,  65. 

"      enlargement  of,  47. 

"      irritable,  65. 

"      rest  of,  65. 

"      sounds  of,  67. 


Heel,  27. 

Hip,  25. 

Hip-bone,  18,  25,  26. 

Hip-joint,  31. 

Humerus,  24. 

Hygiene,  definition  of,  14. 

Hyoid  bone,  23. 

ICE-WATER,  115. 

Incisors,  103. 

Infant,  51,65,  79. 

Insanity,  153. 

Inspiratory  muscles,  132. 

Instep,  27. 

Intestine,  large,  99,  100. 

Intestines,  movements  of,  -10. 

14          small,  100. 
Intestinal  juice,  109, 
Iris,  171. 

JOINTS,  31,  32,  33. 
Jaundice,  109. 

KIDNEYS,  alcohol  in,  118. 
Knee-pan,  26. 

LACHRYMAL  canal,  170. 
"  gland,  171. 

Lacteals,  101,  112,  114. 
Lamb,  79. 
Larynx,  130,  137. 
Lead  pipes,  86. 
Lead-poisoning,  86. 
Leg,  25,  26. 
Length  of  life,  44. 
Lens,  170. 

Lesser  circulation,  66. 
Levers,  17. 
Lids,  171. 

Ligaments,  24,  32,  33. 
Liver,  alcohol  in,  118. 

work  of,  108. 
Lobsters,  80. 
Long  sight,  173. 
Lower  limb,  divisions  of.  25. 


INDEX. 


201 


Lower  limbs,  number  of  bones  in,  19. 
Lung,  appearance  of,  127. 
Lungs,  bleeding  from,  47. 

"      structure  of,  123,  125, 126,  127. 
Lymph,  112,  113. 
Lymphatic  system,  112,  114. 

MARROW,  28. 

Matrix,  161. 

Meat,  79. 

Medulla,  143. 

Meibomian  glands,  171. 

Membranes  of  the  brain  and  cord, 

145. 

Metacarpus,  24. 
Metatarsus,  27. 
Milk,  79,  82, 101. 
Minerals,  85. 

absorption  of,  112. 
Molars,  103. 
Mosquito,  149. 
Motor  fibers,  150. 
Mouth,  99,  100. 
Mucous  membrane,  99. 
Mumps,  105. 
Muscle,  biceps,  41. 

"       contraction  of,  42,  43. 

"       effect  of  alcohol  on,  48. 

"       gastrocnemius,  41. 

"       heart,  ('A. 

"       involuntary,  40,  42,  43,  99. 

"       of  alimentary  canal,  101. 

"       pectoral,  41. 

"       sartorius,  41. 

"       stapedius,  41. 

"       voluntary,  42,  43. 

"       weight  of,  45. 
Muscles,  40. 

"        breathing,  50. 

"        covering  of,  41. 

"        of  digestive  organs,  50. 

"        expiratory,  132.    - 

"        inspiratory,  132. 

"        number  of,  41. 

"        of  the  eye,  172 


Muscles,  of  the  face,  47. 

"        shapes  of,  41. 
Mustard,  88. 
Mutton,  79. 

NAILS,  160. 

Narcotics,  88. 

Nasal  fossre,  128. 

Nerve  action,  rate  of,  148. 

"     centers,  146. 

"      fibers,  147. 
Nerve-cells,  147. 
Nerves,  optic,  170 

•'        origin  of,  145. 
of  smell,  128. 
Nervousness,  151. 
Nervous  system,  action  of,  147,  150 
Nitrogen,  78,  122. 
Nose,  127, 128. 

"     breathing  through,  129. 
Nucleus,  44,  53. 

OATS,  80,  81. 
(Esophagus,  99,  100, 
Old  age,  death  from,  51. 
Opium,  91,  92. 
Orbits,  170. 
Os  innominatum,  25. 
Oxygen,  52,  123. 

in  the  blood,  134. 
Oysters,  80. 

PALM,  24. 
Palpitation,  66. 
Pancreas,  109. 
Pancreatic  juice,  101, 109. 
Papilhe,  158. 
Paralysis,  153. 
Parasites,  79,  83. 
Pastry,  83,  84. 
Patella,  26. 
Pease,  81. 
Pelvis,  18,  26. 
Pepper,  88. 
Pepsin,  117. 


202 


INDEX. 


Pericardium,  61 

Periosteum,  29. 

Perspiration,  159,  161. 

Phalanges,  24,  25,  27. 

Pharynx,  100- 

Phosphate  of  lime,  30. 

Phosphorus,  78. 

Physiology,  definition  of,  13,  14. 

Plants,  78,  79. 

Plasma,  54. 

Pleura,  133. 

Poisoning,  184. 

Pons  Varolii,  143. 

Pores,  158. 

Pork,  79. 

Porter,  93. 

Potato,  81. 

Processes,  20. 

Pulmonary  circulation,  66. 

Pulse,  71,  72. 

Pupil,  171. 

Pylorus,  107. 

RADIUS,  24. 

Raw  meat,  83. 

Reed-organ,  138. 

Reflex  acts,  149,  171. 

Repair,  51. 

Reptiles,  blood-corpuscles  of,  53. 

Respiration,  121. 

"  principle  of,  125. 

Rest,  52. 
Retina,  170- 
Ribs,  22. 
Rice,  80. 

Right  lymphatic  duct,  112. 
Rum,  93. 

SACRUM,  19,  20. 
Saliva,  105. 
Salt,  85. 
Scapula,  23. 
Sclerotic,  170. 
Sensory  fibers,  150. 
Sewage,  86. 


Shaft  of  bone,  29. 

Shell-fish,  80. 

Shin,  26. 

Shock,  182. 

Shoes,  proper  construction  of,  28. 

Short  sight,  174. 

Shoulder,  23. 

Shoulder-blade,  23. 

Shrimps,  80. 

Silver,  78. 

Singing,  139. 

Skeleton,  16,  30,  31. 

Skin,  156. 

"     uses  of,  161. 

u     a  cooling-apparatus,  164. 

"     care  of,  105. 
Skull,  19. 
Sleep,  51,  52. 

"     lack  of,  151. 
Sloth,  the,  53. 
Smell,  nerves  of,  128. 

"      organs  of,  19. 
"  Smokers'  heart,"  90. 
Sneezing,  149. 
Snoring,  129. 
Speaking,  139. 
Spice,  88. 
Spine,  21. 
Spinal  canal,  18,  20. 

"      column,  19. 

"      cord,  18,  143,  145. 
Sprain,  33. 
Starch,  80,  81. 
Staying  power,  46. 
Sternum,  22. 

Stimulants,  45,  88,  151,  166. 
St.  Martin,  116. 
Stomach,  99. 

"         changes  in.  117. 

glands  of,  106. 
"         location  of,  106. 
Stoop,  21. 
Strength,  45,  46. 
Students,  174 
Sugar,  82. 


INDEX. 


203 


Sulphur,  78. 
Sunstroke,  182. 
Sweat-glands,  158,  164. 
Synovia,  32. 

Synovial  membrane,  32. 
Systemic  circulation,  66. 

TAPE-WORM,  79,  83. 

Tarsus,  27. 

Taste,  organs  of,  19. 

Tea,  89. 

Tears,  172. 

Teeth,  102,  103,  104. 

Tendons,  41. 

Tendon  of  Achilles,  41. 

Thigh,  25. 

Thigh-bone,  26. 

Thorax,  18,  22. 

Thoracic  duct,  112. 

Throat,  99,  100. 

"       use  of,  129. 
Thumb,  25. 
Tibia,  26. 
Tiger,  103. 
Tobacco,  48,  90. 

"        effects  on  the  appetite,  90. 

"         effects  on  growth,  34. 

"        effects  on  the  heart,  90. 

"        effects  on  the  lungs,  139. 

"        effects  on  the  muscles,  48. 

"        effects  on  the  skin,  176. 

"        effects  on  the  stomach,  90. 
Tooth,  structure  of,  104. 
Trachea,  structure  of,  130. 
Transfusion,  55. 
Trichina,  83. 
Trichinosis,  83. 
Tricuspid  valve,  63. 
Trunk,  number  of  bones  in,  19. 
Turnips,  82. 
Tympanum,  168. 

ULCER  ATION,  116. 


Ulna,  24. 

Upper  limb,  divisions  of,  23. 

"     limbs,  number  of  bones  in,  19. 

Valve,  mitral,  64. 

"      tricuspid,  63. 
Valve,  semilunar,  63,  64. 
Veal,  79. 
Vegetables,  81. 
Veins,  60,  61. 

"      flow  of  blood  in,  69. 

"      jugular,  69. 

"      differ  from  arteries,  70. 

"      pulmonary,  63. 

"      strength  of,  71. 
Vena  cava  inferior,  61. 

"        "      superior,  61. 
Ventilation,  137. 
Ventricle,  left,  64. 
Ventricles,  62. 
Vertebra,  19. 
Villi,  111. 

Vision,  organs  of,  19. 
Vitreous  humor,  170. 
Vocal  cords,  138. 
Voice,  cultivation  of,  138. 

"      organs  of,  137. 
Vomiting,  107. 

WASTE,  51,  52. 
Water,  52,  85. 

"      absorption  of,  112. 

"      distilled,  85. 

"      poisonous,  86. 
Wheat,  80. 
Whiskey,  93. 
Wines,  93. 
Wine,  adulteration  of,  93. 

"      home-made,  93. 
Winking,  149. 
Worry,  151. 
Wound,  54,  70. 
Wrist,  24. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 

Return  to  desk  from  which  borrowed. 
This  book  is  DUE  on  the  last  date  stamped  below. 


JAN  1 3  1954 
JAN  1  5  RECD 


LD  21-100t»-7,'52(A2528sl6)476 


id   Jfa ! I U 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


